"talent" is not often used in plain English to mean a person. It is correct, but not often used, in this way.
"Talent" usually means the skill, not the person. He has a talent for the piano. He has a talent for driving.
Talent as a person, usually means a person with some specific talent (skill). Someone talented.
This is used in casting & recruitment sometimes. We need a voice talent for voice-over work.
"Genius" usually means a person who is very smart. This does not mean that they are good at anything, just smart. They could be good at things, but being a "genius" does not imply it. Originally, "genius" meant an IQ over a specific number.
Used commonly to mean someone is smart.
Can say, "He is a maths genius." meaning that he has some talent for maths.
In this casual way;
He is a maths genius & he has a talent at maths come out very similar. You see the words are used slightly differently, though.
Hope this helps.