と: This is more like "Theres this AND that." Those two things are everything there is.
や: This is more like "There this and that and someother things that i wont bother mentioning". Theres more than two things there but you dont care to say them.
For example. If you were at school and you did 6 subjects, you wouldnt want to sit there saying "I do english and maths and japanese etc." If you wanted to say everything you'd use と.
If you only want to say a couple of subjects, you'd be like "I do drama and ipt, and other things". Obviously you cant just do 2 subjects, so theres other things you're doing that you're not mentioning. や is used then.
Oh oh... better example. "I have a father and a mother and an older sister." That is と because you arent leaving anyone out.
"Technologies found in the house are TV's and microwaves and toasters and washing machines." They are only some of the technologies found in the house because there is too many to list. Thats why you use や.
Hope that helps a little. と is for and when you say everything, や is for and when you say some of the things.
