it doesn't mean a whole lot in the grand scheme of things. good actors will be good actors no matter the background. using a random example because the two used to be married and were in multiple films where their (excellent) acting can be directly compared: Kenneth Branagh trained at RADA and was so talented he performed a soliloquy for the Queen once as a student, Emma Thompson never trained (she studied English at Cambridge) but got her start working in many comedy series and in a West End musical.