One was Italian, dark and handsome, gregarious though with a tendency to overindulge with alcohol, drugs and women. The other came from the province of Minsk, was noted for his uncouth manners and poor personal hygiene. Both were Jewish and, in the early years of the 20th century, both moved to Paris, which was very much the centre of the art world, in order to further their artistic careers. There they met and became close friends. Now, works by both the Italian artist, Amedeo Modigliani, and the Lithuanian, Chaim Soutine can be seen in two different, major exhibitions in London.

Modigliani is the subject of a showing that opens next week at Tate Modern. Born in Livorno in 1884 into a middle-class Jewish family who had recently declared themselves bankrupt, Modigliani moved in 1906 to Paris, where he lived until his death at the tragically young age of 35 of tubercular meningitis.

The exhibition brings together almost 100 works by him including a number of sculptures that he produced early in his career before his ill health and lack of financial resources made it impossible for him to continue carving in stone.

The highlight of the exhibition will be the inclusion of 10 of his famous, provocative nudes. Modigliani painted his beautiful models completely at ease with their nudity and in particularly sensual poses. These works caused so much outrage when shown in 1917, probably because of their body hair, that the police censored the display on the grounds of indecency. Reactions to them are very different today. One of this series sold for £113 million at auction in 2015, making it one of the most expensive art works in the world.

According to the exhibition’s co-curator Simonetta Fraquelli, “Modigliani is a very popular artist, very much liked by the general public. But his work does deserve to be studied and revisited. There has not been a major exhibition of his work here since 1963. It is timely for the general public to see the work again and look at it with a fresh eye.”

The exhibition will feature a number of Modigliani’s portraits of other artists living in Paris at the time who were friends of his. Most were foreigners, including the Mexican, Diego Rivera and the Spaniard, Pablo Picasso, some were Jewish, such as sculptor Jacques Lipchitz and painter Moise Kisling. Many Jewish artists from Eastern Europe moved to Paris to escape antisemitism in their birth countries. Modigliani formed close friendships with many of them. “He was very proud of his Judaism and very vocal about it. He was part of the Jewish artistic community but also slightly different as the first time he experienced anti-Jewish feeling was in Paris,” says Fraquelli.

Chaïm Soutine was Modigliani’s best friend. Some found this friendship surprising as they came from such contrasting backgrounds and had very different personalities.

Soutine was the 10th of 11 children of a deeply religious clothes mender and grew up in the predominantly Jewish village of Smilovitchi. He got into trouble when he drew a portrait of a religious old man. When the sons of the man took offence to him creating this “graven image” and beat him up, his mother demanded — and received — compensation. With the roubles acquired, Soutine left his birthplace to study art elsewhere, first in Minsk, then in Vilna, finally arriving in Paris in 1913.

There are many stories about Soutine’s bad temper and poor personal hygiene, among them one that a severe earache was found to be caused by a bedbug that had lodged in his ear and had to be removed by a doctor. Perhaps his most famous works are the beef carcass paintings of 1925.

Eventually, the meat began to attract flies and his neighbours complained to the health authorities about the smell. When they paid a visit to Soutine’s studio, the authorities were persuaded to allow the carcass to remain in place but taught him how to inject the meat with formaldehyde to arrest the decay.

Soutine was introduced to Modigliani in 1915 and Modigliani encouraged his dealer Zborowski to support his new friend.

Barnaby Wright, curator of the Soutine exhibition says the friendship “was absolutely vital at a time when Soutine needed a friend. Few people believed in him when he arrived in Paris. And, famously, on his death-bed Modigliani apparently told Zborowski: ‘Don’t worry, in Soutine I am leaving you a man of genius.”’

The exhibition at the Courtauld Gallery focuses on the portraits that Soutine painted of young men working in the hotel and restaurant trade. It is the first time these works have been the focus of an exhibition and the first major exhibition in this country devoted to the artist for 35 years.

Wright suggests why he was so attracted to these subjects. “Perhaps because he identified with them as many of them were like he was, immigrants trying to make their way in French culture.

“I think they were a painterly challenge for him, both for their characters and the colours of their uniforms but also in that basic challenge of portraiture to find and respond to the individual, to resist painting them simply as generic types.”

While the show is smaller than the Tate exhibition with 21 works, each painting is absolutely magnificent, Soutine’s use of colour and texture creates images of young people who look old before their time, suggesting to some extent the premature ageing that hard work brings.

Some look nervous while others “manspread” their legs, confidently filling the canvas. Soutine’s work was very influential on the work of the next generation of Jewish artists working in London. Lucian Freud, Leon Kossoff and Frank Auerbach all cite Soutine as a key influence.

One of these paintings lifted Soutine from the poverty in which he had lived for the first decade of his time in Paris. In 1923, the American collector Albert C. Barnes saw one of Soutine’s paintings of a pastry cook and wanted to see more by the artist. He bought some 50 works on the spot, thus creating an overnight reputation for the artist. With his new-found wealth, Soutine was able to stay in the hotels and eat in the restaurants where he found new models for his paintings.

Unfortunately, Soutine’s style attracted a fair amount of xenophobia, as Wright explains. “People in France were very quick to identify Soutine as a Jewish outsider and, to his supporters, that was a very exciting thing to be, someone who could really embrace the French tradition but shake it up with an outsider’s perspective, not just run along familiar lines.

To his detractors it was impossible to assimilate his work within a French tradition. If people wanted to criticise Soutine they criticised precisely on the grounds that he was a foreigner and his art was ugly and monstrous.”

I ask both curators if they think the two artists influenced each other. Fraquelli mentions that, before Soutine began his paintings, “Modigliani was already painting young people such as the Young Peasant included in the exhibition and Soutine may have been influenced by those pictures when later he began painting his portraits of cooks and hotel workers. But Soutine was painting landscapes down in the South of France and Modigliani, for a brief moment, painted landscapes, too, though we only know of four.”

So, in that case, there is the possibility that Modigliani was influenced by Soutine. Wright adds that “on first sight, their work is very different. Soutine is very expressive, Modigliani more monumental and stylised, but both artists show deep engagement with their sitters and their willingness to distort the figure, in Modigliani’s case elongating and stretching the face inspired perhaps by African sculpture and Soutine getting obsessed with one feature such as an ear and focusing on that.”

‘Modigliani’ opens at Tate Modern on 23 November and continues until 2 April 2018

‘Soutine’s Portraits: Cooks, Waiters & Bellboys’ continues at the Courtauld Gallery until 21 January 2018