Well depsite the fact I think you should hold off on getting a snake of decent size until you can properly house it when you get out of school...
Well firstly there are many different localities of Bci as well as Colombian. That asides the differences between Colombian Bci and Bcc are minimal. They are both the same size on average, being around 6-8.5' in length. I find Bcc to be less tractable in terms of them being more insecure off the ground which translates to more spastic movements, even with regular handling. Both can be docile or biting at anything that moves, but generally Bci are easier to acclimate to handling as youngsters. If you want a handleable snake, make sure you get it as baby. Generally Bcc have more colour to them than Colombians do, as well as shaplier saddles. Bcc have less than 22 saddles, Colombians can also have less, but often have more. Colombians are supposed to be the hardier of the two subspecies.
Bcc (Guyanese)
<img src="http://www.ssnakess.com/photopost/data/508/22poopypants12_12_03-2-med.jpg">
<img src="http://www.ssnakess.com/photopost/data/508/22poopypants31.jpg">
<img src="http://www.ssnakess.com/photopost/data/508/22andora-head.jpg">
<img src="http://www.ssnakess.com/photopost/data/508/22guyanese2-med.jpg">
<img src="http://www.ssnakess.com/photopost/data/508/22satabriab01-med.jpg">
Colombian
<img src="http://www.ssnakess.com/photopost/data/508/22chas1-1m.jpg">
<img src="http://www.ssnakess.com/photopost/data/508/22bci1-4.jpg">
<img src="http://www.ssnakess.com/photopost/data/508/22chasey1-med.jpg">