What's the difference between wa and ga?

The particle wa indicates that the noun preceding it is the topic of the sentence. In most of the model sentences given, the subject and the topic of each esntecnce coincide; however, the topic may or may not be identical witht the subject. Adverbs and direct objects mau becaome the topic, also.
The particle wa may sometimes indicate the meaning of contrast. In general, when wa appears with a noun at the sentence initial position, it has the meaning of topic; otheriwse, it has a contrastive meaning.
The particle ga is the subject marker. In meaning and function it si different from wa. When interrogatives are the subjects of pronominal questions, only ga occurs after the interrogatives, and the partical wa never occurs there.

Thank you for using the Jiskha Homework Help Forum. In addition to the great explanation by Jessica10, here is my favorite site on particles:

http://www.timwerx.net/language/particles.htm