In the packaging they look almost the same, but when swatched they appear a bit different. Captivate (Smashbox) is a lighter peachy pink colour, but with similar undertones to Superstar (e.l.f.).
Both are a warm rose, although superstar is a bit brighter but blended out, each give a nice flushed look. They also contain some reflects, to give a bit of a glow to the skin without looking like a glittery mess.they're also a semi-matte finish. I love that both of them are so long wearing too (4+ hours).
You would probably end up wasting more of Superstar because of the packaging, and just how pigmented even a half pump of this blush is. Like the tiniest of amounts still seems like too much. While Captivate is a bit more forgiving as it is a bit sheerer.
I like the packaging on both of these products, and couldn't say I'd change either of them as it wouldn't make much of a difference to the product. I use both of interchangeably, but to be brutal, I'd pick the Captivate because it's so much easier to apply without overdosing on colour.
Disclaimer: These products were bought with my money. Opinions are my own.