What kind of clothing is "Smart Casual"

like jeans and a sweater type of thing (smart casual) vs. than more business oriented wear like work pants and a blouse and maybe a blazer (business casual)

"smart casual" is used here as opposed to just "casual" to: 1. Sound like we're more "elevated" than just regular casual, 2. Make sure people don't just come wearing leggings and a t-shirt to work everyday

IncomingIBDreject here's what I wrote before. The forum focused on whether women should wear high heels to work or not. I don't usually wear high heels to work, but some around me do for various reasons. Appreciate you calling on me for this topic!

Now back to the main topic for OP:

If this is your first time going into the office (assuming you're a male), I'd wear suit pants, with a white shirt and dress shoes, but no tie (and maybe a jacket, but even that might be too formal. at the same time, never hurts to be too formal, so your call there). If people around you are more casual than you after the first day, I'd continue to wear dress pants (ideally grey or a lighter color) and dress shoes (ideally brown), with a dress shirt (white, blue, pink, any color that looks acceptable), and maybe a vest if that's the environment you work in.

You could even go more casual with the pants and wear either slacks, chinos, or the Lululemon ABC Pants that everyone seems to wear, but that might be a bit casual for the vibe you may want to portray. I'd avoid jeans, unless they are particularly commonplace in your office. I'd personally stick with dress shirts and brown dress shoes, however. 

That said, if it really is casual, wear what you feel comfortable in. And if you need advice, just ask your manager and coworkers for some fashion tips!

Let us know how it works out!