I think that random-wise they should use the same algorithm and type of seeding, thus yielding similar results, although I don't really remember if the arguments are inclusive or exclusive, which may yield slightly biased results depending on such cases, since there would zero chance for the max value to ever be returned for exclusive ones.
For instance, I checked in the wiki (bear with me, been a while) and the Rand seems to be exclusive, meaning that it will return a random integer between 0 and Max-1, while RandRange seems to be inclusive, meaning that there's also a chance that it will return the Max value itself.
However it doesn't matter much what the wiki says, as this can easily be tested: create 2 integer arrays with 10 elements each for example, and run about 1000 iterations, with each iteration running a Rand and a RandRange, one for each array, between 0 and 10, and increment the value of the corresponding array index, then output the results to the log in the end.
This should clearly show if there's any biasing going on, and if the arguments are inclusive or exclusive.
Otherwise if you are expecting it to be inclusive and it's in fact exclusive, Max will never be returned, while if it's the other way around, and if you're using it for arrays (which sounds like it), it may result in a warning and malfunction of your code since it may end up returning Max after all which would correspond to non-existing array index.