Sorry if this is a rather basic question ... but I need to get myself from LAS to YYZ, route is operated by WestJet but also available via AA codeshare.

So e.g. AA5142 from LAS to YYZ is actually WS1117

Booking via WestJet I'm being quoted $365
Booking via AA I'm being quoted $571

Q: If I'm arriving in LAS on an AA flight are there any benefits to booking my onward travel via the codeshare e.g. can I check bags straight through to YYZ? ...or does the codeshare not make any difference?