650c wheels bicycle (for 5'3 and under)

Hard to tell, because it depends. Each brand is different.
With 650c you can make the top tube approx. 1" or a bit more shorter and keep more standard frame angles.
What frame builders tend to do with very small frames for 700c wheels is making the seat tube very steep and the head tube very shallow.
With 650c wheelss the geometry can be more moderate.

Frame height 49cm vs 50 cm doesn't say anything at all.

I did a blog post about my two race bikes -- same brand, similar model, same frame size, but one is 650c and the other 700c. It's been interesting to compare them.
http://smaryka.blogspot.com/2010/05/p2sl-project.html

In a nutshell, the 700c has toe overlap (which I don't mind as I'm used to it -- I have more a problem with that with slow cornering like in cyclocross), a taller front-end to accommodate the taller front wheel, less saddle-bar drop and a more relaxed seattube angle. I ride/race it when I need to share tires/tubes/wheels with other people, and on longer rides where I want to be a bit more relaxed and upright.

The 650c has no toe overlap, a taller seattube angle, and a lower front-end so more saddle-bar drop. It feels zippier to accelerate and climb because of the smaller wheels. I much prefer it for racing but only when I can have my own spare 650c wheels handy in the service car. It's also lighter and nimbler for crits and hill climbing than the "big bike". And more aero.

If I could only choose one bike to ride forever based on sheer joy and love, I would go with the 650c bike. I feel like it just fits me better and is an all-around better built bike geometry-wise, even though the 700c bike is the best frame I've ever ridden in that wheel size (most small racing bikes avoid toe overlap by having a shallow fork angle and seattube angles, which feels to me like I'm driving a bus around corners... ) But sadly 700c wheels are what everyone else rides so I need to be flexible! So I have a mix of both size bikes for different purposes.

By the way, neither of my race bikes are women-specific design, Cervelo doesn't believe in that hype so just tries to build bikes within the constraints of modern cycling (like wheel size) in a geometry that can both perform well and fit people. But I do think both the Fuji Track SE and the Paul Milnes CX frames are more or less marketed as kids' bikes. :)

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