No, all seeds are not the same. Most seed dealers are selling commercially produced seed. Then there are wild simulated and woods grown seed producers. The difference is \"basically\" the amount of chemicals and or cultivation practices used in the growing of the plants and also the genetics.
You need to get seed that meets your intended results. This can be difficult because all are not honest of origin.
At least you should get seed that is from your area, for the obvious reasons.
I suggest to get it straight from the farm.
guy