Greyhound and Lynx are two separate bus systems. Greyhound is City to City and Lynx is the name of the local transit system for the Orlando Area.
Greyhound has two terminals that are near WDW, one in Orlando and one in Kissimmee. Kissimmee is about 17 miles away from the TTC and Orlando is about 20 miles.
There maybe a Lynx bus that could take to WDW*. The route that goes there stops at DTD and then the TTC.
One note while you should be able to take your luggage on the Lynx bus realize that its a City transit bus and you would have to take it with you on the bus. Once at the TTC, if you are planning to go to a Park or DTD, where you can then get a Disney bus if you are going to a Disney Resort, they frown on taking luggage on Disney Buses. Not sure if they would stop you though if you just had a few pieces.