When it comes to terms like having a connection or good chemistry with someone ..

I think there's a difference.

Connection is "I get you"

Chemistry is "I have a physical reaction to you."

Difference are there only if you go into the details of technical and lexical meanings. Otherwise they mean to say same thing. Moreover every person can draw their own separate definitions. The word chemistry is more explanatory and common these days.

I think good chemistry means you work well together or get along together.

Connection is more intimate

One surly leads to the other 😏

chemistry is important at the beginning of a relationship but a connection develops over time and is about understanding