How to Detect a Schema difference (Dataset1 has X attributes, Dataset2 has X+or-n attributes)

Very much a newbie. I'm somewhere around week two of actually touching FME. Have Searched the Transformers and Knowledge base and found close but not quite workflows.

Two Datasets. One published, one to be published (updated).

Need to compare the two. If # of attributes changed(addcol/deletecol) between the two, stop on error. Not caring so much about # of Records, data gets edited so those can change, care about attribute additions/deletions. This is step0.1 of a potentially complex data validation process that will likely take quite some time to develop the full flow. But need to start from somewhere.

Tester - pass = Both files have identical # attributes, and attribute type.

tester - FAIL = Different # of attributes, AND/OR attribute type difference

existence of fail halts process with error - "Illegal Schema Change".

Thought this would be a easy fast one to come up with....not so.

Thanks so much in advance, I'm going to keep trying different things, If I find something, I'll post.