For a transaction with a single input and output, is there a difference between SIGHASH_ALL and SIGHASH_SINGLE|SIGHASH_ANYONECANPAY
A one input/one output tx signed with SIGHASH_SINGLE|SIGHASH_ANYONECANPAY can still be modified to include more inputs and outputs, as long as the original input and output are not modified.

A tx signed with SIGHASH_ALL cannot be modified at all, and no new inputs or outputs can be added.