Slightly longer, but still high-level answer.
Trust is very good at giving mucho flexibility with asset distribution. Also avoids probate.
You need to convey assets into the trust for it to be effective.
Will is important if you have kids and want to designate someone to be their bosses if you die.
Will also has the ability to push the assets into the trust that you forgot to convey into the trust.
Will is cheap and easy to do and important. Trust is more complicated and also important.
My $.02.