Question, for a Vortec 350, what are the difference'* between the stock, high volume, and high pressure oil pumps?

One is the base version, one pumps more oil, and one pumps at a higher pressure.

I kinda figured that. But, application wise, why are there 3 different types and why/what would they be used for?

high pressure oil pump=some serious oil pressure!!! lol

some people think more is better. the stock one is fine. unless you plan on changing the oil pan which i doubt you have room for

You need to keep in mind the chevy small block is the most raced engine in history and one of the cheapest to build. The reason they offer different options of oil pumps is because there are so many ways to build your SB. If your building a high revving low friction motor I would go with the high volum but keep in mind if it pumps the oil fast it needs to return to the pan fast. I have seen guys starve their race motor of oil because the oil couldn't get back to the pan fast enough. The high pressure pump is the most used pump in a performance application because if you raise the compression it puts a ton of strain on the rod bearings and you want to keep them oiled well. Also the high pressure pump helps if you go with a hydrollic cam because it will help keep the lifter pumped up and open the valves better at high RPMs. If you engine is stock and the internals are in good shape the stock oil pump should be just fine under "normal" driving conditions.

So I guess redlining sideways around a corner in my S10 isn't considered "normal" driving conditions eh? J/K.

No, I'm looking at re-ring kits at Summit and I'm seeing different types of pumps offered. Wasn't sure which one to get.

If you do rebuild it I would go with the high pressure pump. I put one in my truck when I did the engine swap about 4 years ago. The lower end had about 100k on it but the rod and mains looked good so I had the heads done, replaced the cam and lifters and put the high pressure pump in. In summer running 5w30 it has about 40psi at idle. Before I changed the engine running 20w50 it would go down to 10 PSI at idle. The RV cam I used said right on the box "not for use in 87 and newer vechiles" the only thing I noticed is it stumbles at idle once in a while.

So the high pressure pumps are compatible with the 96+ Vortecs? I read somewhere that they tend to blow seals out and actually rob quite a bit of HP. Doesn't matter anyway, I'm not looking to turn this into a 1000hp engine anyway LOL.

Yup same oil pump since 1955. I can see it being hard on the rear main but if you run light oil I think you would be fine. If you run heavier oil it can be hard on the cam and dist drive as well because of the added drag the pump uses for the higher pressure. But if you run synthetic light weight oil I don't think you would have any issues. The only time I have seen issues is when the oil pressure get above 100 psi.