Good info above by somdforever.
I'll add:
Babe Ruth merged with Cal Ripkin in 1999. Cal Ripkin is for kids up to 12 and Babe Ruth is for kids 13-18 but they are both the same league.
LL has the same base and pitching distances up to age 12, (60' base paths and 46' pitching distance).
Cal Ripkin changes to 70' base paths and a 50' pitching distance at age 11. They feel it's better to have 11-12 year olds playing on 70/50 fields so it's not such a big adjustment when they get on a "real" baseball field, (90/60), at age 13.
All that said, it really depends on where you live.
In St Mary's for example LL has two separate "leagues", the American in the North and the National in the South. If you play LL you sign up for either the American or National depending on where you live. There is only one Babe Ruth/Ripkin league in St Mary's.
"Most" of the Babe Ruth/Ripkin fields are in the north. They do play some games at Chancellors but most will be at Leonardtown, 7th district or Laurel Grove. If you live in Ridge then it's quite a hike to play Babe Ruth/Ripken ball. The National LL has some fields down in Ridge that would be much more convienent if you lived down that way.
Here are the links to the respective leagues.
Good luck.
ST. MARYS BABE RUTH LEAGUE : Babe Ruth League Online Babe Ruth
St. Mary's American Little League St Mary's American LL
Saint Mary's National Little League St Mary's National LL