say for example you are fishing a 6" plastic worm. if you are fishing a piece of structure, i.e. a dropoff or something, what is the difference between texas rigging the worm with a bullet sinker and dragging it on the bottom and carolina rigging it with about a 2 foot leader and dragging it on the bottom?  the reason i am asking is because i dont have a different pole for every possible presentation. if there isnt much of a difference, its easier for me if i fishing a t-rig worm around a piece of cover like a dock, then just turn around and throw the same rig along a creek channel or something similar and fish it just like a c-rig.

For me, the t-rig is good for throw to specific targets (such as like you said docks).  A c-rig is for dragging around and "searching" for structure that you can't see.  They both have there place, but I believe the t-rig is much more versatile than the c-rig.  If I were you I would just stick with a t-rig because you can't throw the c-rig as close to the cover as a t-rig.  That is just my opinion though.

They both are an equally important part of my fishing arsenal. I use the t-rig and c-rig in a lot of the same places. Docks, points, flats, just to name a few. They both have completly different actions with the same result in the end. Fish in the livewell.

I will even use the c-rig on the trunks of laydown trees that are long without the big mess of smaller limbs. If it has a few bigger limbs, like a laydown that has been in the water for a long time and started to decompose somewhat, the c-rig will come through it just fine. I have took a lot of bass out of trees with a c-rig. It is not just for use as a search bait.

BOTH have their place on my  boat. It is nice to get the lure deep and it still have the weightless appearance that you get with the c-rig. The slower fall is sometimes is what is needed to intice the strike. Other times it is the quicker hopping or bottom hugging action that you get with the t-rig.

The c-rig is mainly a deep water bait for me and I love to throw it right into brushpiles.The object of that is to get your weight temporarily hung on a branch and thats when the magic starts.Once you get the weight hung and stabilized,all you do is start pulling on it lightly and letting back off,then repeating.That makes the branch move and being "hung" keeps your bait in the right spot---------->hovering right over the brush.The fish are naturally curious and when you create a commotion down in 15' + of water,they will come find out whats going on.It's better to leave it down there a little while just to give them time enough to find it.

I mostly use the t-rig to probe deep into laydowns along the bank when the fish seem to be buried in there or around docks when the fish are relating to the bottom......it gets down quick and you can present it with a little less noise when trying to get it in tight places.

I'd compare a T-Rig more to a jig than I would a C-Rig.  C-Rigs are an extremely useful search and destroy tool as to where T-Rigs are more practical punching into cover much like a jig.

I make it real simple:  A T-rig for vertical presentations and a C-rig for horizontal.  For example, I'll use a T-rig to fish specific pieces of cover-laydown, flooded tree top, etc. but I use a C-rig to cover water, work the edge of a weedline or drag it across a point where I need a horizontal presentation.

My choice between the two is based on bottom cover. If there is grass on the bottom which we have in alot of lakes I will throw a crig to keep my bait just above the grass. If it is a cleaner bottom my choice is a t rig. The depth of the water does not really matter to me. I have throwm a T rig in standing timber that was 40 ft but a clean bottom. I have have used a C rig in 2 foot of water because there was alot of grass in the lake. For me cover and bottom tell me what I need to throw.IMO