Unless you're looking for detailed specifics, the basic answer is that there's likely no difference that you'll notice. Both will give you excellent results and both include time base correction.
I've not looked into the 55, but have done comparisons between the 110 and the 300. There, the biggest difference is the Timebase corrections offered in the 300. These are for corrections to things like color balance and gamma, that are done at the time of capture. For a couple $100 more, these can be done, prior to getting the captured footage into PrE/PrPro. However, one can still do the CC and Levels in the program, rather than before its there. For me, the ADVC 300 is worth the $, but one needs to be doing enough of this type of work, to justify the price.
I'll look at the ADVC 55, and see what it might lack, that would be in the ADVC 110.