Whats the difference between arithmetic geometry and algebraic geometry?

both seem to be about geometry. why the distinction? I mean which preceded the other? Why is algebraic geometry more popular?

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This question is too broad. There are plenty of ways to get a basic understanding using Google. – Qiaochu Yuan Aug 18 '11 at 0:39
Algebraic geometry has many more applications. – André Nicolas Aug 18 '11 at 1:09
Is this second comment for real? I hope it is just a joke. – Matt Aug 18 '11 at 1:11
I never heard the term "arithmetic geometry" until maybe 20 years ago, roughly the time of Wiles' work on Fermat. The term "algebraic geometry" goes back quite a bit farther. – Gerry Myerson Aug 18 '11 at 1:15

I recently heard a possible distinction: arithmetic algebraic geometry tends to deal the arithmetic of algebraic varieties (reduction mod p, etc.), especially abelian varieties, in which case an integral model may not be provided or is not the main focus, whereas straight up arithmetic geometry focuses primarily on those integral models, the (especially flat) schemes over $Spec\mathbb{Z}$. However it's possible that Diophantine geometry is actually the proper term for the first description I gave. Would anyone care to comment? – PrimeRibeyeDeal Dec 12 '15 at 21:42