If you enter Epcot through the main entrance you will have to exit through an entrance in World Showcase (near Great Britain). From there, it's about a 10 - 15 minute walk. Actually very beautiful place to stroll. You can also ride the boats to the hotel.
The walk from BC to EPCOT is literally five minutes. You enter through the International Gateway entrance. It is a very easy walk and a great location.
If you take the monorail or bus to Epcot, you need to enter the park to get to BC.
If you don't wnat to do that (use a day on your park ticket), you can take a bus to MGM and then take the boat or walk to BC. Yo do not enter any park to do that.