Difference between znam and wiem?
Both translate to the same thing. What's the difference?
The examples provided by my preceedesors are useful, but the distinction between "znać" and "wiedzieć" is not purely about the topic, but can also be influenced by the way it's expressed. Let's see the way we know a certain method:
"Znam język angielski" – "I know English" (much more common)
"Wiem, jak mówić po angielsku" – "I know how to speak English" (mostly theoretical, but still valid)
Forgive me if I am about to write something stupid, as I'm writing this without any research into the topic, but I feel that when you can (in Polish) immediately follow the verb for "know" with its object, you use "znać". If it would require a preposition or something, then use "wiedzieć".
As a native speaker (I am Lithuanian) sometimes I'm stuck between them too and I use "znam" in context as I would use it when speaking Russian. But I feel the difference, like, znam you use more when you "know" someone (a person), and wiem when you "know" something (any fact, etc.).