Difference between different rocks?

So I went to my LFS yesterday (the only one in town other than Petco and Petsmart) and was looking at the rocks and am confused on the differences. Unfortunately, the guy who was helping me didn't know too much and he said the guy who knows more wouldn't be in for quite a while so I've come here for help!

I took pictures of some of the different rocks and their prices and here's what I have:

Base rock $2.49/lb
Lace rock $2.59/lb
Liferock shelf $6.99/lb
Liferock original $5.89/lb
Liferock shapes $9.69/lb
Liferock branch $7.89/lb
Real reef live rock $9.99/lb currently on sale for $5.99/lb
Marco rock (I don’t know the price)


I'm about to start a tank and don't really know which rocks to get. The "real reef live rock" was the only stuff in a tank. Most of those were purple-ish. The various "Liferocks" were underneath and were also mostly purple-ish. What is this Liferock stuff? And how does it differ from base rock and lace rock, which are both tannish in color? There was also a big box of Marco rock, also tan in color. What is Marco rock?

I was planning on getting some live rock and some "base" (or dry?) rock but now I don't know exactly what is live and what is "base" after seeing these varieties.

Any help would be greatly appreciated!
Cody