MaxDiff is used when you have an independent set of items, i.e. I have 20 ice cream flavors and I want to know what are the best ones. You can put things related to taste, cost, presentation, etc. into a MaxDiff and figure out how each item relates to the other one (i.e. great taste is more important than a fancy plate). We never ask any sort of combined questions, though, so it's not appropriate in MaxDiff to combine item scores together (i.e. a chocolate and vanilla cone is better than a strawberry and mango cone). You can additionally use the output of a MaxDiff into TURF analysis like our MaxDiff Analyzer to figure out what bundle of items "reaches" the greatest number of people.
Conjoint analysis is probably the better tool when you have a multi-piece product or service, i.e. Product A costs a lot but taste great and looks good, versus Product B which is cheaper but doesn't taste/look as good.