No, not at all. Just glad we can help. "P" stands for passenger tire. "LT" stands for light truck tire. Now you might be thinking "Well I need LT tires on my truck, right?" Ehhhh, maybe, maybe not. LT tires are basically thicker, stronger, and slightly less flexible so that they can handle significantly higher pressure and have a higher load index or weight handling capacity. Think of it as heavy duty. The only people that really NEED LT tires are people that tow or haul considerable weight on a regular basis. I would guess the majority of half-ton trucks on the road have P tires and the vast majority if not all new half tons are sold from the dealer with P tires. There is nothing wrong with running P tires on a half ton pickup if you don't need LT tires. By the same token, there is nothing wrong with running LT tires even if you don't need them. You are very unlikely to tell the difference from behind the steering wheel in every day driving. But that is why they are more expensive.
As to whether 275/60 or 275/65 is best for you....I would guess it's going to come down to appearance. Unless you tow a large boat or trailer or similar or routinely haul mulch or rock or whatever with your truck, you don't NEED an LT tire. If that is the case, the only benefit to the 275/65 for you is that it is slightly taller and fills the wheel well a little more. If you have a need for the LT rating or if you think you might want to level the front of your truck and if you can afford the price difference, I would go with the 275/65. If you do not have a need for the LT rating and aren't going to level it and/or price is a big factor, go with the stock 275/60.
If you google image search "Dodge Ram 275/65/20" you can find some trucks with them to see what they look like. Just be sure to read the article or forum thoroughly because it will bring up a lot of results where that size tire is mentioned but not what is on the truck in the photo.