What is the difference between Country music and Bluegrass?

I tend to think of bluegrass music as something played on lutes and banjos by barefooted men in denim called Zeke but I may be confused here. While I hum "You're in the Jailhouse Now" and look for my copy of "Oh Brother Where Art Thou", you might find the following site and its links more useful for distingishing Country from Cajun, Bluegrass, etc. :
https://en.wikipedia.org/wiki/Bluegrass_music

https://en.wikipedia.org/wiki/Country_music
- basic info about the country music genre: alternative, bluegrass, country rock, cowboy, early-country, rockabilly, folk, honky tonk, Nashville sound, new country, new traditionalism, outlaw, traditionalism, western swing

Well, Bluegrass is mostly instruments, while Country Music is like Rascal Flatts and Kenny Chesney, kinda on the pop side.