how are smart phased transactions different from smart contracts?
In a nutshell, a smart contract allows you to write code to do just about anything (including potential dangerous stuff).
Advantages are you have a lot more freedom to do whatever you want, the drawbacks is obviously security (if you have a bug in your contract someone could exploit that), and thus it will require more time to learn to code properly & test your contracts.
With smart transactions you don't write any code, the functions are already pre-defined within the protocol. You just pass in your desired parameters.
The advantages are the opposite of smart contracts, it's more secure, it takes less time for you to learn, code & test.
The drawbacks is that you are limited to the functions that exists in the core client.
Not sure if that makes any sense, or if it is even the correct definitions.
It is my understanding anyway.