best to google the difference but here is the general difference from my knowledge
i don't know much about tanganyikan or victorians so hopefully someone with more knowledge can fill in
Mbuna are generally small (few bigger then 5-6 inches average 3-4) bottom dwellers that live in areas covered with bottom rock clutter. ideally the bottom of the tank should be covered with rocks that reach high in the water column. As a group mbuna are generally the most aggressive and territorial cichlids from malawi. They need a high plant diet or they develop diseases like bloat and constipation.
Haplochromids, or haps are open water predators and prefer more open space then mbuna. they appreciate some rocks for territory boundaries but they are open swimmers and need space to move. they are generally the predators of malawi and usually grow 5-8 inches but some can grow up to and over a foot. Haps are generally not too aggressive with other fish but they can be mean with others of the same species or sharing appearance. stick with the smaller species for a 55
Peacocks are open water fish like haps but they are generally smaller, averaging 3-6 inches with few growing up to or larger then 8. they live in open sandy areas and often feed on either plankonic organisms, invertebrates, and prey in sand. They live in schools in the wild and if you have a good male female ratio you could probably keep a small school. they are similar in aggression to haps and are among the least aggressive rift valley cichlids.
the aggression rules are similar with CA cichlids with males being meanest to other males. Avoid mixing different species that look very similar or they will fight often. either pick one male of each species you want for all male tanks or have a 1:3 or 1:4 ratio male to female since they are polygamous and males will pretty much constantly harass any females to spawn even when not ready. There are some exceptions but I don't know them well but they generally call for even more females to males. for a 55 you could mix haps and peacocks assuming the adult haps cannot eat the adult peacocks. A 55 is too small for haps/peacocks and mbuna. they like very different environments and mbuna are mean little buggers. When haps/peacocks fight for territory the losers are often forced among the rocks. With Mbuna in the mix the lesser hap has no chance as the sanctuary is the far meaner mbunas territory. Mbuna have far better dentition for causing damage to other cichlids in disputes. Another issue with the mix is diet. Mbuna need high plant diet or they get all sorts of intestinal disease haps/peacocks need higher protein diets being more predatory.