"Yesterday, we were playing football" VS. "We played football yesterday"? What's the difference between them?

Introducing myself Hi, everybody :) I'm Tomek and I'm from Poland. I'd love to make new friends from all over the world. My native language is Polish, but I learned English at university. I'd like to improve my English language skills because I have a lot of problem with grammar. I'm also very interested to learn Chinese. I would be very grateful if you could help me. If you want to learn Polish language just let me know, I can help you:) Thanks