What's the difference between batch.size and buffer.size in Kafka producer?

[CRK]

Hello,

    I'm working on developing Kafka producer and I was confused with these parameters:

1) What's the difference between batch.size and buffer.size in Kafka producer? 

2) For ex. if batch.size is 128 Kb, is this the size of each message in one offset in Kafka topics? How does this work exactly?

Thank you!