DVD is?

DVD (also known as “Digital Versatile Disc” or “Digital Video Disc” – see Etymology) is a popular optical disc storage media format. Its main uses are video and data storage. Most DVDs are of the same dimensions as compact discs (CDs) but store more than six times as much data.

Variations of the term DVD often describe the way data is stored on the discs: DVD-ROM has data which can only be read and not written, DVD-R and DVD+R can only record data once and then function as a DVD-ROM. DVD-RW and DVD+RW can both record and erase data multiple times. The wavelength used by standard DVD lasers is 650 nm^[1], and thus has a red color.

DVD-Video and DVD-Audio discs respectively refer to properly formatted and structured audio and video content. Other types of DVDs, including those with video content, may be referred to as DVD-Data discs. As next generation High definition optical formats also use a disc identical in some aspects yet more advanced than a DVD, such as Blu-ray Disc, the original DVD is occasionally given the retronym SD DVD (for standard definition).

Media type	Optical disc
Capacity	~4.7 GB (single-sided single-layer), ~8.54 GB (single-sided double-layer)
Read mechanism	650 nm laser, 10.5 Mbit/s (1×)
Write mechanism	10.5 Mbit/s (1×)
Usage	Data storage, video, audio, games

VCD is?

VCD stands for ‘Video Compact Disc’ and basically it is a CD that contains moving pictures and sound. If you’re familiar with regular audio/music CDs, then you will know what a VCD looks like. A VCD has the capacity to hold up to 74/80 minutes on 650MB/700MB CDs respectively of full-motion video along with quality stereo sound. VCDs use a compression standard called MPEG to store the video and audio. A VCD can be played on almost all standalone DVD Players and of course on all computers with a DVD-ROM or CD-ROM drive with the help of a software based decoder / player. It is also possible to use menus and chapters, similiar to DVDs, on a VCD and also simple photo album/slide shows with background audio. The quality of a very good VCD is about the same as a VHS tape based movie but VCD is usually a bit more blurry.

kbps = thousand bits per second
Mbps = million bits per second
² approximately resolution, it can be higher or lower
~ approximately bitrate, it can be higher or lower
ª DVD with lower video quality, similiar to VCD/SVCD video quality
* the video quality depends on the bitrate and the video resolution, higher bitrate and higher resolution generally means better video quality but bigger file size