There are quite a few differences between the 25 and 27 foot trailers. The International was pretty much a trim package, it would include such things as a relocated oven, different trim, and of course a spiffy "International" badge.
The 25 and 27 have completely different interior configurations, from where the fridge sits to the type of bathroom. A big difference is the 27 could be ordered with a rear bedroom (very rare option), and the 25 was center bed only. Both could have twin or double beds, but the fridge is much smaller in the 25.
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.