The difference would be irrelevant, based on OP’s description. She ought to be able to plug into literally any SQL dialect if she’s doing junior/mid-level analyst work.

I'm not sure that's correct. AFAIK, having deep Oracle knowledge is very valuable to the right employer, but not so much for non-Oracle shops.

From my experience ~20 years ago, Oracle and SQL Server were very different beasts.

IIRC, once you get past trivial querying and into storage design, query optimization, etc., they're very different beasts. And Oracle in particular is it's own, huge world at that level. (Again, if I recall correctly.)

Sure, and I think that would definitely be relevant to a different kind/level of analyst. Sounds like OP’s mom would be more than covered by knowing how to google “Postgres function for whatever”.

I think for most SQL-only analysts, the vagaries of deep Oracle vs. MSSQL or whatever aren’t super relevant.

My own impression is that she who can write PL/SQL can write T-SQL. My own background is largely in Oracle, but I've dealt with SQL Server a fair bit.

I work with both Oracle and SQL Server, and this is absolutely true. There is a common standard you can stick to, but there is also a considerable universe of Oracle-specific features even just in the query language, to say nothing of temp tables etc.

Her title is db admin and that’s the position she’s gunning for. They’re going to expect senior level skill beyond just creating queries.

“ She wants to find a place to be comfy and write some SQL scripts, analysis, and data modeling here and there, where she will be both happy and useful. Pay is not a priority.”

None of this suggests senior level skill to me, whatever title is associated with it, particularly given the three points OP listed that she pushed back on. This role is, at most, mid-level.

GP mentioned Banner. The company that sells Banner (which uses Oracle on the back-end), merged with another, so now also sells a product in the same space that uses MSSQL on the back-end. The product that uses Oracle is priced lower than the one that use MSSQL by approximately the difference in DB license costs, so the two products come out pretty similar for total cost (I've heard that this pricing scheme was intentional to prevent one product line from cannibalizing the other after the merger).

Of the three public higher ed institutions within a 100 mi redius of me, all are Oracle on the back-end, two Banner and one Peoplesoft.

To the OP, your mom can watch university and community college job boards and search for keywords like "Banner" and "Peoplesoft". Banner jobs will likely be either one of, or a combination of Oracle DBA and writing PL/SQL.