3G vs LTE

I've been putting off in getting myself a decent phone for a while. It started with iPhone. Since my wonky old Jurassic age phone was dying, I thought of getting a new one. Not being a heavy user, I didn't like the notion of being tied down by a contract with an exorbitant monthly fee when I hardly yak for hours on the phone. Back to the story. It all started with the legendary iPhone. People (namely nanny goats in the family) have been advising me against getting an iPhone. They're against me having anything anyway. Might as well be Amish. Anyway, when iPhone 4 came out, I wanted to get the phone without the plan. But unfortunately, the apple stores here don't sell them. Only the telcos have them. I was eager to ask whoever who is visiting America or any overseas country to help me get one. Again the impromptu advisors were quick with their brilliant advise that the phone won't work in our country if it's bought overseas, yada, yada. So fine. I'll wait for iPhone 5, which took donkey years to release. Then the sudden passing of Steve Jobs, everything kind of stalled. Then samsung's S3 came along. I was keen on getting it too. Again, a lot of commentary (which nobody asked for )from the advisors. So S3 came and went. Long story. A whole lot of nitty gritty details in which I do not wish to dwell in. So now the S4 is out. First, with the 3G version. Then now, the LTE version. I seriously don't know what's the difference between these two. Im a noob in technology. So if I were to get the 3G version, does that imply that it won't be able to support the 4G when it becomes more common? My concern is that the telcos might be switching to 4G real soon. I don't want my new S4 to be obsolete 3 months down the road. Not to mention the S4 comes with a hefty price tag. The 3G version is retailing  at $2199, whereas the LTE version is retailing at $ 2399/2499(can't remember which). Which is a better choice? The 3G or the LTE? Why do the telcos always have to complicate things? Samsung, why do you have so many variations of the same model? Why do you keep churning out products every quarter? To buy or not to buy? Which one to get?