7.5 Mas vs. 7.5 Mass

I went gunshow cruising today and saw an interesting thing. I found 2 different boxes of FNM-made 7.5 French ammuntion, at 2 different locations. Both were the common Portuguese FNM commercial production. However, one was promintly labeled “7.5 Mas”, while the other said “7.5 Mass”.
Not really earth-shattering, but interesting none-the-less. No, I didn’t get them.