Profession
Profession is, depending on who you ask, an essential part of your time on the server. If you're a diamond seller, a potato farmer, etc there's a profession for it. So, in other words, you playing on the server goes perfectly hand in hand with profession. Every profession have levels, and when you reach level 1.000, something quite special happens.
Prestige
For those who've picked a lot of apples, mined and sold a lot of diamonds, etc, there's a reward. Upon you reaching level 1.000 in a profession, you'll prestige. You gaining a prestige level grants you access to the Prestige Shop. You gaining a prestige level also shows that you've done a lot of work in that single profession, and shows that you're dedicated.