I think he's asking about the bolt specifically....how to tell the difference between LR and AR10.
I don't think you can tell visually. If I remember correctly, people have measured out tiny headspace difference between the two. If your gun checks out, you should be GTG.
If it's an aftermarket bolt with any mfg markings on it, it's probably DPMS pattern. not too many people making AR10 bolts other than armalite.