Sage Mode is basically a straight multiplyer in raw power. It's not exactly stated what the number is, but we know that it offers a "new dimension of power" to the user's chakra and Jirobo, who said that his curse mark multiplied his power ten times over and his curse mark was inferior to Sasuke's.

We arne't told where exactly Sasuke's compares to "real" Sage Mode, but we know the curse marks are inferior to Jugo's bloodline, and that Sasuke at full Stage 2 was able to dead-match Naruto with a one-tail stage version one Nine-Tails shroud.

We do know tha

Differant forms of Sage Mode have differant abilities and differant techniques based on it—The Frogs have Frog Kata, which gives the user an aura that means that even if they miss they can still hit with their aura while the snakes have InaInorganic Reincarnation, which lets them pump natural energy into non-living things and then reshape it.

So, if Usagi gained a form of Sage Mode, her Rabit Sage Mode would be differant from Senko's Sage Mode.

Jugo's sage mode isn't really elaborated on: His Bloodline, Sage Transformation, lets him weaponize his body and alter himself in various ways, but when we see the mastered version of it Kabuto just uses it to power up his Snake Sage Mode and Mitsuki gets snake made of chakra.

Sage mode is apparently tough on the body: Orochimaru just flat out can't use it because his body can't handle it and Mitsuki suffers severe cellular strains when he uses it, as I noted, he held the form for too long and needed to have organs replaced afterward.