We contrast the experimental signatures of low energy supersymmetry and the
model of Universal Extra Dimensions and discuss various methods for their
discrimination at hadron and lepton colliders. We study the discovery reach of
hadron colliders for level 2 Kaluza-Klein modes, which would indicate the
presence of extra dimensions. We also investigate the possibility to
differentiate the spins of the superpartners and KK modes by means of the
asymmetry method of Barr. We then review the methods for discriminating between
the two scenarios at a high energy linear collider such as CLIC. We consider
the processes of Kaluza-Klein muon pair production in universal extra
dimensions in parallel to smuon pair production in supersymmetry. We find that
the angular distributions of the final state muons, the energy spectrum of the
radiative return photon and the total cross-section measurement are powerful
discriminators between the two models.Comment: 6 pages, 8 figures, to appear in the proceedings of the 2005
International Linear Collider Workshop, Stanford, US