Is there any significant differences between OSI model and TCP/IP other than the number of layers?

Well, OSI is a model for how things are supposed to "work" when transmitting messages over a network. It is generally comprised of seven layers (though these often get meshed together in function).

In depth, the Open Systems Interconnect is a standard description or, a "reference model" for how messages should be transmitted between any two points in a telecommunications network. Its main purpose is to guide the product implementers, in a way that their products will consistently work with other products. it's basically a standard for the industry.

When the IEEE commitee created the model, it was for, that different vendors/manufaturers products would work with each other. basically its the matrix that TCP/IP originated from.

Since it's creation until the "birth" of TCP/IP, and the rapid evolution and adoption of the protocol, the model as been simplified by those who handle it, in a day by day basis.
TCP/IP is a protocol that performs the work and provides the function of some of those seven layers in the OSI model.

Today, some of the layers have been meshed, since they are basically handled in the same way, Layers 3 & 4, are more than normal to become one.

Significant differences? Absolutely.

If you have the patience to read the vast collection of standards regarding the OSI model.
Check the ISO.org website, specifically this link:
http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html

Specifically the ISO/IEC 7498, 8072, 8073, 8348 and 8602.

Hope it helped.

my 2cents....