Yep. There are degrees of maturity.
The flat podded snowpeas, round podded snap peas, and shelling/green peas.
Snowpeas are easy to differentiate because the pods remain flat. You still need to decide what level of maturity you like. Best way realiy is to pick and eat them. Some snowpeas will develop string if left to mature too long, then you would have to string them before eating -- but sometimes, there is more flavor in those mature peas and pods.
Same for snap peas. One daughter likes the peas inside to be more mature and starting to develop sweetness. Otherwise, she complains they taste too "green".
I thought that the distinctive waxy shape of snap peas will be distinguishable from tough shelled shelling peas, but it turned out that it's not always easy to tell. So I do plant them away from eachother now.
Shelling peas are my kids favorite. But if you pick them too immature, they taste "too green" and if too mature, the "too starchy". There's nothing like green peas at just the right maturity, picked and eaten in the garden. --- I have to taste test them to be sure they would be acceptable to my kids, right?
When I bring them in, I put them in the same bowl as the berries -- I only cook the peas if there are any left over (I freeze them and when there are enough, I cook and serve. Usually there are very little peas left and sometimes, there are more berries left than peas.
I also save peas for seeds -- those are left on the vines until they are dried up. I usually wait until quite late in the season because if you don't keep picking, the pease stop producing. By then, the pods start to get shriveled and number of peas in the pods are diminished. But this year, I'm thinking of selecting designated seed plants which will be allowed to mature without picking. This way I'll be able to save the realiy good looking pods.
If I have enough dried peas, I sort them into best ones for planting, and eat the smaller ones. This year, I'm growing Blauschokker Blue peas which are listed as "soup peas" but are also edible as immature pods. And Marrowfat peas which are also supposed to be harvested as mature peas.