Field Advantage follows the same basic principles as Hand Advantage, but with a few key differences and variations.
Field Advantage usually does, but not always mean, how many monsters you have on the field, compared to your opponent. Spell and Trap Cards present on the field do not count to such a large degree as monsters, because Mass Spell and Trap Removal is so prevalent in this format, compared to the limitation of Mass Monster Removal, since Dark Hole's Ban, although Torrential Tribute still presents a threat in this regard.
Gameplay and Glossary