Summary
When you see jungle trees that were naturally generated in a Jungle biome (and variants), they usually have a lot of vines on them. Except for large jungle trees, where they generate leaves ONLY on their trunk and not their leaves, regardless if they were grown via sapling or generating naturally. As for small jungle trees, ones that generate naturally have a lot of vines on them. But if you grow said small jungle trees via sapling, they don't generate leaves at all.

Steps to Reproduce

1. Get 5 Jungle Saplings
2. Place 1 by itself, and the other 4 in a square.
3. Wait for them to grow. (Or if you're impatient, use bonemeal)

• The small jungle tree doesn't generate any vines, inconsistent when they naturally generate in a biome without the use of saplings.
• The large jungle tree generates vines only on their trunks, but not their leaves.

Observed Result
The small jungle tree doesn't generate any vines at all, and the large jungle tree doesn't generate vines on its leaves, but instead generates them on its trunk.

Expected Result
The small jungle tree should had generated its vines, and the large jungle tree should generate vines, regardless if it was grown with a sapling or generated naturally in Jungle biome.