A 32-bit operating system can only support up to 4GB of RAM. 64-bit allows more than 4GB, giving increased performance. It also allows you to run 64-bit apps.
Error-correcting code memory can detect and correct data corruption. It is used when is it essential to avoid corruption, such as scientific computing or when running a server.
Dynamic frequency scaling is a technology that allows the processor to conserve power and reduce noise when it is under a light load.
It is easier to obtain better performance when using virtualization if it is hardware-assisted.
A technology integrated into the processor to secure the device for use with features such as mobile payments and streaming video using digital rights management (DRM).
AES is used to speed up encryption and decryption.
Out-of-order execution is used in CPUs to make use of instruction cycles that would normally be wasted due to delays.