COALESCE or CASE more efficient and/or standard

Question

In terms of x compared to y.

• Does x comply with sql standards better? [apologies if subjective]
• Is x more efficient than y?
• Or are these

Answer 1

COALESCE is essentially a shorthanded CASE statement.

Both are exactly the same.

There is also ISNULL in SQL Server (differs in other DBMSs), but that's actually a non-standard feature and is actually more limited that COALESCE.