"There is a tall wardrobe in my room."
Translation:W moim pokoju stoi wysoka szafa.
To a degree – „stoi” is just more precise; with „jest” it's merely within the confines of your room, it could be laying on the floor instead, it could be Ikea wardrobe totally in pieces, waiting until you will spend the mandatory 4 days to put it together and so on, while „stoi” establishes that it indeed stands.
That said, „stoi” is within meaning of 'there is', we do use it somehow interchangeably with „jest” – I guess it's because in 90% of cases, wardrobe just stands there, where it „jest”. ;)
It's important to not start a "There is..." sentence with "jest". It's not wrong per se, but it's really unusual. In Polish you start those sentences with the location.
Unless the sentence is just "There is a wardrobe." as an answer to "What is in your room?", then of course that's just "Jest szafa".