Identifying character traits for Tom Sawyer and Huck Finn requires considering their actions and the intents behind those actions. Finding similarities and differences can be challenging, but they are present.
Both boys were loyal to their friends. When Tom Sawyer's Gang was formed, Huck was in danger of being excluded since he had no family members who could be executed if Huck gave away gang secrets. However, Tom and the others wented Huck to be a part of the gang and figured out an alternative that allowed him to be a member in good standing.
Both boys loved a good adventure. Whether it was pretended activities, as when Tom Sawyer's Gang "lay in ambuscade" waiting to kill and plunder the "whole parcel of Spanish merchants and rich A-rabs," or the efforts undertaken to free Jim from his prison on the Phelps farm, there was never any question that both would be enthusiastically and energetically involved.
Tom was the more imaginative, but in some ways the less kind-hearted of the two. Freeing Jim could have been quite straightforward and simple if the boys had followed the plan Huck had developed before Tom arrived. Once Tom was on the scene, however, he insisted that all the proper steps in the process of breaking out of prison be observed - even when they weren't needed and in fact made things much more uncomfortable for Jim.
"Jim, don't act so foolish. A prisoner's got to have some kind of a dumb pet, and if a rattlesnake hain't ever been tried, why, there's more glory to be gained in your being the first to ever try it..." "Why, Mars Tom, I doan' want no sich glory. Snake take 'n bite Jim's chin off, den whah is de glory?..." "Well, then, let it go, let it to, if you're so bullheaded about it. We can get you some garter-snakes and you can tie some buttons on their tails, and let on they're rattlesnakes, and I reckon that'll have to do." "I k'n stan' dem, Mars Tom, but blame' 'f I couldn' get along widout um, I tell you dat. I never knowed b'fo, 't was so much bother and trouble to be a prisoner."