You can use different versions of the SVN client (TortoiseSVN) and the SVN server (UberSVN) together. This is also the case with just plain Subversion as well. So your Client can be at a higher or lower version number than your server, and vice versa. You can read more about the "inter-compability" between versions here in the Subversion documentation.
The version numbers help to distinguish between bug fixes and API changes. Typically when the MAJOR.MINOR numbers of a given Subversion version change it's telling you the type of change that occurred. For bug & security fixes the MINOR number will change. For more drastic changes to the API or new features, the MAJOR number will change.
These changes typically don't impact the core functionality, so you can still use Subversion client version 1.5 with Server version 1.7, for example. In most cases the client will simply ignore any extra information that a particular feature may offer, if the server is at a higher version number.