What is the difference between Hyperledger sawtooth core and Hyperledger sawtooth sabre?

I am new to blockchain technologies. We have bided against the potential project on hyperledger. So I was reading the documentation of hyperledger Sawtooth. In the documentation, I found Sawtooth core and Sawtooth Sabre. From the documentation , in a layman term I can make out that Sawtooth core provides you the platform and Sawtooth Sabre is a way making smart contracts.

My question is :

1. Is my understanding right?
2. Can I use smart contracts i.e. Sawtooth Sabre with Sawtooth core.(Any documentation, any reference, please provide)
3. Can you please point out some good study materials for the same.
4. Is Sawtooth is the right choice instead of fabric.

#hyperledger #blockchain