Not the same card though you can use them at either store, but you can only get cashback from the store the card is from, so you can only get cash back at Walmart with the Walmart card, and only get cash back at Sam's Club with the Sam's club card.
Only the Walmart card comes with free TU fico once a month. Both will grow with you even if you start out small it will grow.
I think they give out cards with about a 650 or higher, possibly lower with a good relationship with GE money bank and/or high income. If you fico is above 720 they may offer you the discover version. Upgrades of the Walmart store card to Discover card usually takes a year or two. And are GE initiated no way to request as a customer.
You may find an instore offer of $20 or more cash back with your approval for the card and you spend $100, getting such deals when you apply online is more difficult.
So in store is usually best, a pre-approved offer may pop-up when you are checking out at Sam's club.
Did you have a high score when you applied? Just not sure how much I trust the TU credit score of 764 it gave me.
Mine was around 700 when I got the Sams Discover $2500 CL
The Sams version usually gets a higher CL but the Walmart version gets you the free FICO. Get the Walmart version. The CL will climb very fast being a GE card.