CFR stands For Custom Flat Ride such as Merry-Go-Rounds, Ferris Wheels and such and CTR stands for Custom Track Rides which is Roller Coasters and such
Two of the best websites to find Cfrs and Ctrs:
A place to find RCT2 Cfrs and ctrs:
http://ae.rctspace.com/Rct3:
http://www.vodhin.org/e107/download.php?list.41 To find the ctrs in the vodhin.org page push the link to the downloads and look for custom track rides.
Instructions on how to download:
To download These in Rct2 go to the rct2 folder open or save the ride in the folder named Data. Then boot up the game. at the main menu go to the icon tools then push the create a park. Go down the list of attractions when you enter and search for the name of the ride.
For Rct3 go to the rct3 folder the style folder and create a folder named Custom for cfrs and you open the file and save the folder with the name of the person in the folder. Then boot up the game and go into Sandbox and check the icons of ride most of the time in Thrill Rides and it should be there if you did it correctly. For ctrs read the readme's to find where to put the ctrs
Rct2 CFR example:

CTR:

Rct3 CFR example:

Ctr:
