Which is better for small chests?

The Lift Up Bra. It is cut for AA to B cups and owners say it gives lift without cup gaps. SKIMS covers a wider size range but is not shaped specifically for small chests.

Which one can be worn strapless?

Only the Lift Up Bra. Its straps detach, so it works under strapless and off-shoulder tops. The SKIMS bra has fixed back straps.

SKIMS is the safer bet. Owners of the Lift Up Bra report cup material tearing or fraying after the first wear or wash, and it needs hand washing. SKIMS is machine washable with a concealed underwire.

Is the SKIMS bra worth stepping up to?

If you want a plunge neckline, side smoothing and machine washing, yes. If you need strapless wear or a bra made for small cups, the Lift Up Bra fits that job better.

Do either run true to size?

Both run tight in the band. The Lift Up Bra advises sizing up for a less snug band; SKIMS advises going up one band size if you are between sizes.

Which gives more lift?

The Lift Up Bra is a dedicated push-up with a half-cup design and reports of real cleavage. SKIMS adds up to one cup size with teardrop pads, which is a more balanced, natural lift.

Pepper Lift Up Bra vs SKIMS Ultimate Teardrop Push-Up Bra

Buy the Lift Up Bra if you wear an AA to B cup and want a strapless-capable, detachable-strap push-up built for small chests. Buy the SKIMS Ultimate Teardrop if you want a plunge bra with concealed underwire, compressive side wings and machine washing. Both run tight in the band, so most shoppers should size up. The Lift Up scores higher with owners (4.6 vs 4.1), but complaints about tearing and fraying are common; SKIMS is the sturdier, easier-care pick.

Choose the Lift Up Bra if you are an AA to B cup who wants a gap-free push-up that can go strapless.
Choose the SKIMS Ultimate Teardrop Push-Up Bra if you want a plunge neckline, smoothing side wings and machine-wash care.

Prices

Pepper Lift Up Bra: $65.00 at Pepper (checked today)
SKIMS Ultimate Teardrop Push-Up Bra: $64.00 at SKIMS (checked today)
Difference: the SKIMS Ultimate Teardrop Push-Up Bra is $1.00 cheaper than the Pepper Lift Up Bra today