She's FINE
If she was in the 5th or 25th for height and 95th for weight... then there might be a problem to be addressed.
Typically, though, not even a blip if it's within 1/3 of each other (and you're 1/4), and no concern until it's 1/3 (like 25 & 75 or 50 & 100)
You know the whole "all babies are different' thing? This is that. Your other daughter was already a couple months into crawling (huge gross motor) and walking (huge gross motor)!!! Betcha anything you like, though, that THIS one is more advanced than your other daughter in one of the following
- fine motor (includes verbalizing)
- cognitive (includes a LOT; from language recognition, "physics" -object permanence, gravity, cause & effect, etc.)
- emotional
- sensory
- visual
Babies don't develop on a straight line, they leapfrog about focusing on different areas in different orders from each other (hence the HUGE spread of time in milestones). No baby can be doing ALL areas of development at once. So your first got really hipped on gross motor young, I'm curious what your 2nd has been hipped on? Just for fun/ curiosity... but what has #2 been reveling in? She's obviously just gotten hipped on gross motor if she's crawling and cruising... but what about before? Check the list above. And you'll have your answer.
Babies don't start slimming out until they
1) Hit a long gross motor phase &
2) Toddler years when their ribcage expands enough for their organs to move upward under it (the toddler 'potbelly' and 'toddler walk' is created by their organs being mostly in their belly, instead of protected (and hidden from protruding out) under their ribs.
Somewhat counterintuitively... tablefood can cause EITHER a lot of weight gain (because the body goes into starvation mode, because there's not enough nutrition in it to support rapid growth) OR weight loss (because there's not enough nutrition to support infant's rapid growth). It tends to be weight loss for a few weeks, and then they balloon up all roll-y poll-y, and then they get all lethargic and thin, and then they balloon up again. As a matter of fact, one of the causes that's being studied for childhood obesity is "starving" infants by filling them up with tablefood (looking ANYTHING like starving, but table food just isn't nutritionally dense enough), but limiting formula or breast milk. If this is a pattern you're noticing with #2... it's an easy fix.
As long as her primary source of nutrition is breastmilk or formula... you really don't need to worry. But if 1/3 or more of what she's eating is table food (or if she's having table food FIRST, then formula)... reverse things for awhile. More formula, and formula FIRST.
2nd kids are often super chubs because they're in starvation mode (because we get used to feeding our toddlers, and it becomes habit to feed the babies table food before formula)... but a 1/4 spread, I wouldn't be too concerned.