Garb vs Costume

[Lady Anne Clare]

I personally don't like the word costume as it makes me think of polyester cheapies from Walmart at Halloween.  But that's just my preference, so I don't use the word to describe someone's clothing that they have put time into.  Whether it's purchased or made with their own hands, time and care went into making it. But if someone else refers to my outfit as a costume, I'm fine with that as long as they weren't trying to be snarky.  A compliment is a compliment.

[LadyAsh]

When I think of "costume" I think of the type of outfits only made for Halloween. I use the term garb to describe my faire clothing. It's something that I can wear more than once or twice a year, if I like, plus the chemises make really good nightgowns.

[Capt Robertsgrave Thighbiter]

 To us, Garb is Renn Faire clothing. Amoung most pirate re-enactors, the word Kit is used most often, to describe not only clothing but the accoutraments of a desperate sailor.  Since we tend to perform at more pirate fests, we kinda have picked that up.

[Captain Dungcaster]

I do World War One reenacting and kit is what we use. You have a uniform and web gear, ammo pouches,canteen etc.. and a rifle.

By the way I do a WWI Australian impression.

Frank Blanton

[bellevivre]

when i dress in any semblance of HA, it's garb. mostly, i'm a glitter addict now, so it's a costume. but it's always CLOTHING... and typically, my favorite, at that!

[Jack Daw at Work]

When I "garb" for TRF, I shoot for period-accurate clothing, so I call it "period wear".  But, even a couple of my items are shortcuts for comfort, like my footwear is not period accurate.

[Betty Munro]

A while ago I attended a Pirate Festival with a friend of mine and kids in tow. 
My kid was in a pirate outfit of home sewn cotton pants and linen shirt, home sewn leather vest, decorator fabric pirate coat, real silk sash, faux suede bucket boots, replica metal sword and metal and wood pistols.  I'd call that outfit "garb".
Her kid was in $15.00 Wal-Mart polyester 2 peice Halloween pirate ensemble and sneakers.  I'd call that a costume.
But, that doesn't mean that all costumes are cheap, or that all garb is expensive, well made or extravagent.
po-tay-toes, po-tah-toes
If I wear my pirate clothes to a Halloween party, then it is a costume. 
If I see a man outside of faire or celtic festival in a kilt, then I do the same as I would at those events ... I compliment his bonny knees.    I wish more men wore kilts as everyday wear.  They are so much more attractive than shorts!   

[dreamwalker]

My sister likes to call the cheapo poly halloween costumes slut in a bag costumes. Before I can to this site I steered away from calling it a cotumes cause the clothes were much more to me than that I called them my gear. But now I know I must call them garb and so I do....

[DonaCatalina]

Well, let's define stuff;

cos·tume
Noun:
1. A style of dress, including garments, accessories, and hairstyle, especially as characteristic of a particular country, period, or people.
2. An outfit or a disguise worn on Mardi Gras, Halloween, or similar occasions.
3. A set of clothes appropriate for a particular occasion or season.

garb
Noun:
Clothing or dress, esp. of a distinctive or special kind.

So really it sounds like 'garb' is better than clothing, outfit or costume...

Really, I think it depends on your point of view, I refer to faire garb as 'garb' around the renfaire community, but at home I'll say "time to get out the renfaire outfits".  If I'm at the Sci-Fi con and wear my Men In Black outfit, it's a costume, dressing up at cons is generally called 'costuming'. 
But to the general public, any clothing that is outside of their experience is a 'costume'. They don't know where you're coming from, so you could be dressed as King Henry VIII, or Capt. Kirk, it's a costume to them. So I don't get upset at faire if a mundane says "nice costume", any more than I do when some one says it to me while I'm out running errands in a kilt, I just say thanks and move on.

This came up recently as I was trying to explain Twelfth Night and St Voloc where we go in garb outside of fair.