This is true - these are two completely different things. And I assume from the comments on this post that the OP does indeed define it subjectively, i.e. via loss of (expected) value. Each is worthy of discussion, and I think the two discussions do mostly overlap, but we should be clear as to what we're discussing.

Cases of extinction that aren't existential risk for some people: rapture / afterlife / end of the world religious scenarios; uploading and consequent extinction of biological humanity (most people today would not accept uploading as substiute to their 'real' life); being replaced by our non-human descendants.

Cases of existential risk (for some peoples' values) that don't involve extinction: scenarios where all remaining humans hold values dramatically different from your own; revelation that one's religion or deeply held morality is objectively wrong; humanity fails to populatte/influence the universe; and many others.