What's the difference between emerald tree boas, green tree pythons, amazon tree boas, and cook's tree boas?

what's the difference between these tree snake species, i'm aware that emerald tree boas and green tree pythons are completely different snakes and come from different parts of the world like the tree pythons come from australia and the tree boas come from south america and that the amazon and cook's tree boas are a bit smaller than the emerald and green tree and that the boas give live birth where as the pythons lay eggs but what's like the "main" difference between the amazon and the cook's tree boas? and do amazon tree boas and cook's tree boas make great pets for beginners or are they for more experienced keepers like the emerald tree boa and green tree python is? and do all tree boas and tree pythons require experience and are rather difficult to keep in captivity? I know that all these animals are different and sort of do look the same but i can tell the difference between them but i'm just wondering why were they build the way they are like why do they coil up on branches they're whole life day in and day out just waiting for their prey? and why are these snakes very difficult to keep in captivity?