You're basically right. People can do it in a number of ways, so it's hard to talk about the differences definitively, but the two solutions can be made nearly equivalent -- hw wallet plus pass phrase with PIN, vs SeedQR with pass phrase.

With a QR code, physical possession of the paper decays to the strength of your passphrase. With a hardware wallet, there's still a PIN to get through before that's true. PIN can be much lower security -- it's pretty easy to memorize a 4-6 digit number, allowing for a range of barriers depending on threat model.

With HW wallet, you can write down your seed phrase, or not, as you like. You can use multisig to obviate the need to write anything down at all, which is how Casa does it. Either way, you have, at worst, equivalent security to QR, but you can choose to have more or less.

And practically, it's a quite different affair to give a little electronic doodad to someone you trust, along w/ a PIN, vs pieces of paper and instructions on how to reconstitute from a SeedSigner.

If you want to strawman things, you can make either one terrible.