I would say an SA (Solution Architect) is very different from an SE (Sales Engineer) in one fundamental way: the SA is focused on delivering value post-contract and the SE is focused on making sure the org is able deliver the value promised by working with sales in the pre-contract phase. In some smaller companies or organization within a company, I can see these roles being performed by the same person but in general that distinction between pre and post sales has been my lived experience.