LEVELING & PRESTIGES:
Next to your name you'll see a number and an icon (mainly a star, but you can earn yourself a different icon). This represents your level. You earn level the same way as money, by killing others. Since Levels don't really earn you much but a nice number and a color next to your name (and possible place on leaderboards), prestiges (/prestige) do a better job:

Prestige I - 1.2x Experience Multiplier
Prestige II - 1.3x Experience Multiplier & Ability to sell Emerald for $60
Prestige III - 1.4x Experience Multiplier & Ability to buy Kit Crate Key for $9.000
Prestige IV - 1.5x Experience Multiplier & Ability to buy Notch Apple for $12.000
Prestige V - 1.6x Experience Multiplier & Ability to buy 1st Special Item
Prestige VI - 1.8x Experience Multiplier
Prestige VII - 1.9x Experience Multiplier & Ability to sell Emerald for $70
Prestige VIII - 2.0x Experience Multiplier & Ability to buy Kit Crate Key for $8.500
Prestige IX - 2.1x Experience Multiplier & Ability to buy Notch Apple for $11.000
Prestige X - 2.2x Experience Multiplier & Ability to buy 2nd Special Item
Prestige XI - 2.4x Experience Multiplier
Prestige XII - 2.5x Experience Multiplier & Ability to sell Emerald for $80
Prestige XIII - 2.6x Experience Multiplier & Ability to buy Kit Crate Key for $8.000
Prestige XIV - 2.7x Experience Multiplier & Ability to buy Notch Apple for $10.000
Prestige XV - 2.8x Experience Multiplier & Ability to buy 3rd Special Item
Prestige XVI - 3.0x Experience Multiplier
Prestige XVII - 3.1x Experience Multiplier & Ability to sell Emerald for $90
Prestige XVIII - 3.2x Experience Multiplier & Ability to buy Kit Crate Key for $7.500
Prestige XIX - 3.3x Experience Multiplier & Ability to buy Notch Apple for $9.000
Prestige XX - 3.4x Experience Multiplier & Ability to buy 4th Special Item
Prestige XXI - 3.6x Experience Multiplier
Prestige XXII - 3.7x Experience Multiplier & Ability to sell Emerald for $105
Prestige XXIII - 3.8x Experience Multiplier & Ability to buy Kit Crate Key for $7.000
Prestige XXIV - 3.9x Experience Multiplier & Ability to buy Notch Apple for $8.000
Prestige XXV - 4.0x Experience Multiplier & Ability to buy 5th Special Item
Prestige XXVI - 4.2x Experience Multiplier
Prestige XXVII - 4.3x Experience Multiplier & Ability to sell Emerald for $120
Prestige XXVIII - 4.4x Experience Multiplier & Ability to buy Kit Crate Key for $6.500
Prestige XXIX - 4.5x Experience Multiplier & Ability to buy Notch Apple for $7.000
Prestige XXX - 4.6x Experience Multiplier & Ability to buy 6th Special Item