Flower and bloom mean the same thing i.e the flower is opening its petals. The noun bloom is a synonym for the noun flower. Bloom is only used to describe people in one context; if a person goes through puberty very slowly, they're described as a "late bloomer" Another synonym for flower and bloom is 'blossom.' This word can be used to describe a person, as 'to blossom' means to develop into something. (e.g "Sol was a late bloomer but now she's blossomed into a beautiful, successful woman") Flourish means that the flower is blooming very well and very quickly. This can be used to describe a person because if a person is becoming successful at something very quickly, they're 'flourishing.' (e.g "Wow, Sol only became a painter last month and she's already sold her painting for $1000. Her career is really flourishing!") I'm not 100% sure about all of this; I'm a native English speaker but I'm not a florist!