As mentioned in this old 2014 thread, the real life part and the part in BI have a side stud protruding over the regular 1x1 brick dimensions which was never implemented. It probably should be though since it would be easy to make a model that is unbuildable in reality due to this.
https://forums.ldraw.org/thread-12698.ht...light=4070
There are also a few other differences too in more modern revisions like how the internals are arranged and the internal circular hole depth. It also has those triangular parts which are likely to help hold a bottom stud a bit more securely.
On the right is the BI part and on the left is the ldraw one. I've attached the latest version of the BI part.
![[Image: Screenshot-2025-10-30-101536.png]](https://i.postimg.cc/GhxR1jpT/Screenshot-2025-10-30-101536.png)
https://forums.ldraw.org/thread-12698.ht...light=4070
There are also a few other differences too in more modern revisions like how the internals are arranged and the internal circular hole depth. It also has those triangular parts which are likely to help hold a bottom stud a bit more securely.
On the right is the BI part and on the left is the ldraw one. I've attached the latest version of the BI part.