There are major differences both in gameplay and itemization.
- Lost Souls is set build, second one got more fluid itemization. Everything looks different.
- Skeletons from set got high CD but they are less fragile. No-set build in exchange can spam skeletons if needed.
- Lost Souls utilize dogs as active skill - they can be spammed and bombed into group of enemies, it increase dps. No-set build rely only on skeletons, rest pets are little meatshields.
- No-set build got better survivality on player side due to inbuilt flat RR so other devotion choices can be used.
- Wielding huge two-handed scythe is cool and impossible with lost souls.
Some people still prefers no-set version.
Now differences between both chaos builds.
- Just look at GT both of them: (pure chaos beastcaller) https://www.grimtools.com/calc/Q2zBQdk2 and (chaos birds) https://www.grimtools.com/calc/q2mXmE0N
- Totally another itemization, one is beastcaller set, another is bysmiel jewelery.
- Birds are birds, not Briarthorns.
- Bird build has much lower single target but aoe carry it. It’s based on lightning strike burst and elemental devotions converted into chaos from offhand - all other pets are just supporting meatshields for proccing even more aoe from Leviathan and Fissure. Beastcaller is very high constant DPS but more single-target oriented.
- Birds do not have so high taunt but they are ranged. Gameplay in high SR is different, more kiting is required but it’s not really much dps lose because pets do not need to stay at boss face.
Apart of it even chaos birds are little bit stronger than elemental from my tests and with only 2 items difference both must be played differently and feel like totally another builds. Elemental is heavy dot based, must be played basically like bleed damage, hit and change target. Chaos do not require so much fast target switching.
Well, if these builds are not different than each other then shouldn’t we allow only one DW/2H meele per class? There are even less differences, same autoattack animation everywhere and gameplay