Hello Arev! 만나서 반가워요.
You got a good Question!!
like George said, it's different.
I guess it may be confusing when using it.
Let me explain 이제 and 지금 with one simple sentence. Based on George's definition.
Look at these sentences.
이제 봄이네요.
지금 봄이네요.
In English, it might be same sentence but has different meaning in Korean.
이제 봄이네요. is used in a situation that spring is just around the corner but it's still winter. And 지금 봄이네요. is that it's spring now as you know.
I hope you got my point. lol