Eames contract table base sizes  

Yes
Segmented base.

Contract vs Segmented
Can someone tell me the difference between Contract Base and Segmented Base?

What do you mean
By "contract" base?
These are the two types of bases currently available:
http://www.highbrowfurniture.com/tables/products/dt-round/

4 bases actually
The Contract base was the first base widely used. It is the same base that originally appeared on the Aluminum Group chairs in 1958. It is the same base that is currently on the Vitra version of the Eames Lounge & Ottoman. It is characterized by a slender vertical tine terminating in a rounded pad. (IMO its the most pretty)
In 1968 when the Aluminum Group was updated with the Softpad Group the bases changed. The new bases were thicker, more sculpted, and less angular. The tines were wider and terminated in a droopy teardrop. This base replaced all bases on the Aluminum/Softpad group chairs and is called the Universal base.
The Segmented Table base is a hybrid that was developed in 64. Both the Universal and the Contract bases were for individual pedestals. The Segmented base is a modular system that can be adapted for longer conference tables. The tines are a mix of the Contract - vertical and slender - and the Universal - terminating in the teardrop shape.
All three of the above bases are still in production on tables.
The last base was actually the first, and was only breifly used as a chair/table base. It is currently only used as the base of the Herman Miller Lounge & Ottoman.

Didn't know...
The 4-star base is still in HM production for dining height tables?

I think this is the base you're referring to...
I've had this orphaned Eames chair base collecting dust in the basement for years. I've only ever seen a few pictures of it used on anything but the ottoman. Obviously, this one is meant to support a shell chair. It's a shame they didn't use it more widely, but I'm sure it's more cost effective to forego the two-tone finish.
Any idea about the production dates, fellow DAs? I can tell you that it predates the screw-in domes of silence (it came with the boot style feet that were also used on the 2nd gen ESU).

I got a response from Herman...
I got a response from Herman Miller.
For dining height tables, they have different size Contract bases for 42" and 48" round tables.
However, the same size Segmented base works for both 42" and 48" round tables.