Good question! the two words are very close in meaning. The difference is subtle in American English. “Select” is a bit more formal , not often used in casual conversation. Also, it often refers to choosing one of a small and specific set of options. For example:“ Select a color from the 3 that are displayed.” “Select a time for your English lesson from the following schedule.”
“Choose” is more commonly used and more casual.
I hope this helps!