ESP...EPS...foam question????

I was at home depot and lowes this afternoon picking up stuff. I could not resist looking at the foam seeing how my interest was peaked by discussions here. My question is on the racks right next to each other was foam boards 4’x8’ each…one 2" the other 3/4" . One was labeled eps(expanded poly styrene) the other was labeled esp(go ahead insert jokes here…!) was this a labeling mistake??? Or is there a esp foam(that reads your mind and shapes itself…lol…) no really ,I am serious. Both foams were white,I asked and no blue or pink foam was carried by either store.Are the only “good” foams from dow? These were not from dow. Thanks…