The line between HTIBs and minisystems has blurred in a lot of ways, but to a large degree mini systems are most two-channel systems while HTIBs by definition are almost all multichannel. In a way, the mini systems are more like a nonportable version of a boom box, while HTIBs started as prepackaged component combos, but are now moving more towards integrated designs. The weak link with the vast majority of minisystems and HTIBs remains the speakers, and with an increasing number of HTIBs, that's the exact component that you cannot upgrade. By putting the amp inside the bass module and connecting it to the control unit with a proprietary cable, the designers can miniaturize the main component and make it look sleeker. But, this type of nonstandard design also takes away the upgrade options.

The advantage to mini systems is that they have not gone to this kind of proprietary arrangement, and there are still HTIBs out there that use standard connectors and allow for the buyer to upgrade the speakers. Among the mini systems out there, Denon used to pair their mini system with Mission speakers and the resulting sound was surprisingly good. Denon still makes decent mini systems, but they're now packaged with their own speakers. Another alternative would be to get an integrated receiver/CD/DVD player and add your own speakers.