Hyperthreading is used on certain Pentium 4 chips. it basically tricks the computer into thinking there are 2 CPU's so it will send 2 instructions at a time.
Hypertransport is used on AMD K8 CPU's (Athlon 64's, socket 754 Semprons and Opterons)
it refers to the way the CPU communicates with RAM. instead of communicating to RAM through a memory controller on the motherboard, they have their own memory controller onboard, and communication between CPU and memory controller runs at the CPU's speed.