What is the difference between と and や to join nouns?
日本語 と れきし と か学 を 勉強します。
日本語 や れきし や か学 を 勉強します。
The meaning of the two sentences above is ‘I study Japanese, history and science.’
However there is a slight difference between them. や implies more than what you list. と doesn’t.
So the first sentence tells that the person studies the three subjects only. The second sentence tells that the person may study more than the three subjects.