The main primary difference is hard to pin down to one.

For example majority of existing platforms require a download of some sort to get going. Whereas with BitStash you can use it without any downloads just from your browser.
Verified vendors that have been inspected / visited by BitStash.
Airdrop vendor fees every quarter to token holders.

There are a lot differences and benefits to BitStash compared to the rest. However we are not trying to replace anyone, more so just trying to provide something different to the community and crypto-space.