QVGA:
The Quarter Video Graphics Array (also known as Quarter VGA or QVGA) is a popular term for a computer display with 320x240 resolution. QVGA displays are most often seen in mobile phones and PDAs. Most often the displays are portrait mode (other mode is landscape) and are referred to as 240x320 as the displays are taller than they are wide.
The name is derived from the fact that it offers 1/4 of the 640x480 maximum resolution of the original IBM VGA display technology, which became a de facto industry standard in the late 1980s. QVGA implementations are not compatible with, nor directly derived from, standard VGA chipsets or interfaces; the term refers only to the display's resolution.
VGA
Video Graphics Array (VGA) is a computer display standard first marketed in 1987 by IBM. VGA belongs to a family of earlier IBM video standards and largely remains backward compatible with them. VGA can be seen as an enhancement of and successor to the previous EGA and CGA graphics adapters. MCGA, also produced by IBM, is a simpler version of the VGA hardware.