Since this question was posted, the "Equipment Pack" has been replaced by the "Jumbo Equipment Pack" - basically the same thing but larger. Additionally, a variety of additional different packs have been added.
There are a large number of different equipment packs. In general, the packs available from the multiplayer store grant you items, weapons and powerups, and unlock character classes. Some packs have a focus on a particular type of item, so for example, an Arsenal Pack will have a greater focus on weapons while a Jumbo Equipment Pack will only drop powerups.
It is possible to unlock weapons and characters multiple times, and doing so will upgrade weapons or provide an experience bonus for the duplicate character unlocked.
The various types of equipment pack are as follows;
- Starter Pack - a free, single use pack, that unlocks weapons and characters
- Recruit Pack - unlocks basic weapons, mods, and characters. Includes 5 items with a small chance for an uncommon unlock
- Veteran Pack - unlocks more advanced weapons and mods. Includes 5 items with at least one uncommon item or better
- Spectre Pack - unlocks even higher quality gear, including 5 items or characters with at least 1 rare unlock or better
- Premium Spectre Pack - unlocks even higher quality gear, including 5 items or characters with at least 2 rares unlock or better
- Jumbo Equipment Pack - bonus equipment, includes 10 random equipment and supply items
- Arsenal Pack - Includes 5 random items with at least two rares or better, with a higher chance for weapon unlocks
- Reserves Pack - Includes 5 random items with at least two rares or better, with a higher chance for character unlocks
All packs available in the store (except the Starter Pack) can be purchased and used multiple times with both in game currency and Bioware points.
Additionally, there are a variety of promotional packs which were only available during exclusive events or through special offers:
- Battlefield 3 Pack - A bonus for having Battlefield 3 on your Origin account
- Premium Collectible Pack - A bonus for purchasing Mass Effect action figures
- Collector Rifle Pack - A bonus for preordering the art of the Mass Effect universe
- N7 Day Loyalty Pack - A gift from the Mass Effect team for playing on November 7th 2012
- Recruitment Reward Pack - A bonus for participating in the Mass Effect 3 Recruitment Program
- Vault Reinforcement Pack - A bonus for purchasing the Calibur11 Mass Effect 3 Vault console case
- Collectible Pack - A bonus for purchasing a physical copy of Mass Effect: Paragon Lost
- Gift Pack - A gift from the Mass Effect team
- Commendation Pack - A reward for completing an individual objective during an operation
- Victory Pack - A reward for the community completing the Community Goal during an operation
- Resurgence Pack