Playstyle: Summoner and Black Mage

Can someone explain the primary differences in Playstyle between the Summoner and the Black Mage?

Are they both pure pewpew dps or does one offer some sort of support options?

Black Mage is more DPS focused. It is focused around a gameplay of balancing out an MP restorative weaker-damage ice state and a high damage, high-expenditure fire state. It doesn't have much in the way of party support but, played well, is a nearly endless well of damage output (including what is almost certainly the best AoE capabilities of any class in the game)

Summoner is still DPS, but sacrifices some of its damage capability for other options. Its damage is focused in Damage Over Time effects, but has weak upfront burst and AoE (what Black Mage excels at), and it also has some supportive spells (debuffs/heals). You also get a pet - either an extra DPS source, a tank, or a healer. Also, your base class is shared with Scholar, a healer class, so you'll be able to swap to that whenever you want and take advantage.

In short, Black Mage if you want all the damage; Summoner for a more versatile experience.

That's not quite right as far as SMN goes. They don't really "trade off" DPS capability for support, as both are very capable of support (BLM, for example, can inflict slow, heavy, and sleep). Actually, that's a trend across pretty much all DPS classes. Also, SMN does not get a healer pet, only SCH does. SMN gets one tank pet (Titan) and two DPS pets, a short range one with Ifrit and a long range one with Garuda. Due to a few reasons I won't get into here, Garuda's pretty much always better.

The main difference is how they do their damage. BLM's focus is on powerful direct damage spells, and they are well suited for making sure something dies FAST, as well as area damage. So they're useful for fights where something needs to die in seconds, or where you're facing a lot of little monsters.

SMN, on the other hand, deals damage primarily through Damage over Time spells. These inflict a lot of damage, but over a large period of time. This makes them not as useful for when something needs to die in less than 30 seconds, and their area options are also limited. However, when attacking a single target over a long period of time, they can do an impressive amount of damage.

One other key difference is that with DoT's the SMN is much more mobile in a fight whereas the BLM is basically a case of needing to stand still to cast (not 100% exact as the SMN does have casting timers and BLM do have some instant cast spells, but in general when a BLM is moving their DPS drops a lot whereas a SMN DoT's are still ticking).

In all honesty youll want to level both a arcanist and a thaum at least to 30 in the end sooo try them both out, put them through their paces. Youll know by 30 which one you'll want to main

Yep. Try them both. Heck, you might even end up on a completely different path and go SCH. LOL

I just unlocked scholar and it is a blast so far, running Haukke Manor I am purely doing dps with cleric stance up and my fairy does all the healing except occasional heals from me on the bosses. Im sure this will change a ton in 10 lvls but I think its the most fun job I have played so far.