Simply put, NTSC is the video format used in North America and Japan, PAL is used in Europe and most other countries. Vegas and VideoFactory can import and export both NTSC and PAL video formats.

It's a long and detailed discussion with a ton of references all over the web should you care to dig deeper. Here's a little more info (poached from whatis.com):

The NTSC (National Television Standards Committee) was responsible for developing, in 1953, a set of standard protocols for television (TV) broadcast transmission and reception in the United States. Other standards were adopted in the rest of the world. The NTSC standards have not changed significantly since their inception, except for the addition of new parameters for color signals. NTSC signals are not directly compatible with computer systems.

An NTSC TV image has 525 horizontal lines per frame (complete screen image). These lines are scanned from left to right, and from top to bottom. Every other line is skipped. Thus it takes two screen scans to complete a frame: one scan for the odd-numbered horizontal lines, and another scan for the even-numbered lines. Each half-frame screen scan takes approximately 1/60 of a second; a complete frame is scanned every 1/30 second. This alternate-line scanning system is known as interlacing.

PAL is short for Phase Alternating Line, the dominant television standard in Europe. The United States uses a different standard, NTSC. Whereas NTSC delivers 525 lines of resolution at 60 half-frames per second, PAL delivers 625 lines at 50 half-frames per second. Many video adapters that enable computer monitors to be used as television screens support both NTSC and PAL signals.