What exactly is careless driving? This is the second time i am fined for careless driving. Whats the difference between wreckless and careless driving?

Careless means that you drove to possibly make a dangerous situation. Reckless driving means that you are definitely causing a dangerous situation.

I'd look at the charges, ask the officer what it was that you did, and then review the driving rules for your state and make a change to your driving habits.