What is the difference between QVGA & SVG theme? Since I've tried to install both theme on my E61 devicer and found there is no any diference with the results.

QVGA was the meaning for screen resolution. it's 240x320. but svg was for image format. if the themes was make in svg format. it's will compatible to all phone.

But both QVGA and SVG are installed & worked on my E61, bro!

Qvga themes are for the phones of 240x320 screen size and Svg themes work at the phones of all screen size thats means there is no distortion in image when theme applies at phone of bigger resolution.

But both QVGA and SVG are installed & worked on my E61, bro!

maybe that's qvga themes also using svg image.

QVGA means quarter VGA i.e., quarter of the rectangle of VGA (640x480)
which is the most common resolution (no. of DOTS on the display) of 2 days fones

SVG mean scalable vector graphic.

If a theme is QVGA, it means it is best suited for 240 x 320 (actually 320 x 240, but at ipmart we go the other way) screen
If the theme is SVG, it means its made up of SVG images which will scale themselves if applied to larger resolution phones and there will be no distortion in image

SVG for example work on E90 Communicator and N73 and 3250 even there screen is different in physical size and resolution...
QVGA mean it will work only for the 320x240 resolution this mean only N73 an ddont work on 3250 and E90...
the majority of phones we use has 240x320 screen resolution.