Just woke up so I'm not the most clear headed, but...
Couple features that the Samsung drives have, Overprovisioning, which reserves a little of the drive space (5-10%) for sector reallocation, greatly improving the drives durability and lifespan, and ... Forget the name, it's "turbo" mode that can increase the speeds, making it close to the fastest SSD on the market (I think OCZ still hold that crown, but the durability of their top performance drives is low).
I don't know about mushkin, but Sandisk (one of the other popular "cheap" high capacity drives) make their drives cheap yet fast enough by relying on the cache to maintain high speeds. This means that sequential read speeds and small file write speeds are high (IIRC) but as soon as you start dealing with large files or random read/write, performance drops by half and come out near the bottom of the tables. Still very good value for money, especially with how often they go on sales (I picked up 3 during Black Friday).
And to vaguely answer the open question about the anatomy of an SSD, 3D Vertical is Samsungs technology for stacking the NAND chips to improve capacity without sacrificing speed and durability, TLC IIRC is triple layer cells (however the access method for the cells makes it triple as likely to wear out and fail), SLC is single layer cells (the best for access speeds and lifespan, but too expensive per chip so it's reserved for enterprise drives), MLC and eMLC I can't remember but they're the most common to find, and X-point is what's coming out in 1-3 years that'll improve speeds by around 1000x without sacrificing lifespan (like an evolution of 3D).
There are four main parts to a SSD, the NAND which stores the data, the cache for queuing access commands, the CPU and controller which are the brains of the drive. To find out what makes a good SSD, you need to know what type of NAND it has, who made the NAND, what controller it has, and how many cores the CPU has. IIRC, the CPU and controller tend to come on the same chip these days (in early gens they were separate).
I'm sure I missed out many things or got some things mixed up, but I'm too groggy to do the research from my iPad first thing in the morning.