CD
VG condition - Under a normal light the CD surfaces may show some signs of light wear and may have very light scratches ... If placed under a magnifying lens more scratches may be visible than just to the naked eye
G condition - Under a normal light the CD surfaces may show some heavier signs of wear and may have more noticeable scratches
Case
VG condition - almost looks like new
G condition - case scratched but no damage to it ( ie cracks or pieces missing )
POOR condition - case very badly scratched or may have damage to it