Minecraft wiki entry for Development_versions, associated text: Advanced OpenGL is enabled by default in this version. In Beta 1.6 Advanced OpenGL was removed temporarily until Beta 1.6.5 due to bugs.
Advanced OpenGL will crash Minecraft on some computers.
Picking up multiple stacks of items takes a few ticks to finish, unlike the final version where it only takes one.
The fix for the crash when riding a vehicle or animal through a nether portal is done differently.[verify]
Session requests are performed over HTTP instead of HTTPS.
Session requests fail on any code other than HTTP 200, instead of only with HTTP 400.
Connection to the server is closed differently; no thread is used in this build.
GL state when rendering items is not properly reset, which may lead to graphical artifacts.[verify]
Tall grass renders differently: