"View" - Inline Disposition – opens in built-in viewer in same tab
"Download" - Attachment Disposition – opens in built-in viewer in same tab (Fx98-100) or new tab (Fx101)
"Download" - Inline Disposition + Download attribute – opens in built-in viewer in same tab (Fx98-100) or new tab (Fx101); in Fx101, download attribute file name (bugzhone.pdf) does not carry over when saved from the viewer, which should be fixed in Fx102 (bug 1767321)
"Download" - Blob + Download attribute – opens in built-in viewer in same tab (Fx98-100) or new tab (Fx101); in Fx101, download attribute file name (bugzblob.pdf) does not carry over when saved from the viewer, which should be fixed in Fx102 (bug 1767321)