is there a difference?

between a red tail boa and a columbian boa? or is it just called differently by different people?

Correct me if I'm wrong but I believe that a true red tail is a BCC=boa constrictor constrictor. I also recommend you to visit the following sites http://www.theboaforum.com/cgi-bin/yabb/YaBB.pl and http://forum.redtailboas.com/ they are mainly focused on boas.

A Columbian boa IS a red tail boa. However, there are lots of different red tails besides Columbians. There are two different types of red tails. A Columbian is a BCI (Boa Constrictor Imperator) and is more suited to a beginner keeper. (They're not as big and are easier to care for.) The "True" Red-tails are the BCC, as Danny mentioned. They get much bigger and are less forgiving of husbandry mistakes. Their tails tend to be a much brighter shade of red, which makes the nickname of "red tail" fit them a bit better than it does the BCI.

Yes and no :)
Colombian boas (Boa Constrictor Imperator) are commonly referred to as red tail boas in the pet industry. They are not "true" red tails though.
The true red tails are the (Boa Constrictor Constrictor) that display a lot more red in thier tails as adults. They also get a lot larger than their colombian cousins. Some examples of true redtails are Suriname and Guyana boas.

thx for making that clear guys