Using a multi-phase transport (AMPT) model that includes the implementation of deformed Uranium nuclei, we have studied the centrality dependence of the charged particle multiplicity (N ch , dN ch /dη), average transverse momentum ( pT ), eccentricity (ε2), triangularity (ε3), their fluctuations, elliptic flow (v2) and triangular flow (v3) for different configurations of U+U collisions at midrapidity for √ sNN = 200 GeV. The calculations have been done for both the default and string melting versions of the AMPT model. The results are compared to the corresponding observations from Au+Au collisions. We find that for the U+U collisions the dN ch /dη at midrapidity is enhanced by about 15-40% depending on the collision and model configuration chosen, compared to Au+Au collisions. Within the several configurations studied, the tip-to-tip collisions leads to the largest values of N ch , transverse energy (ET) and pT . The ε2 and its fluctuation shows a rich centrality dependence, whereas not much variations are observed for ε3 and its fluctuations. The U+U sideon-side collision configuration provides maximum values of ε2 and minimum values of eccentricity fluctuations, whereas for peripheral collisions and mid-central collisions minimum values of ε2 and maximum value of eccentricity fluctuations are observed for body-to-body configuration and the tip-to-tip configuration has minimum value of ε2 and maximum value of eccentricity fluctuations for central collisions. The calculated v2 closely correlates with the eccentricity in the model. It is smallest for the body-to-body configuration in peripheral and mid-central collisions while it is minimum for tip-to-tip configuration in central collisions. For peripheral collisions the v2 in U+U can be about 40% larger than in Au+Au whereas for central collisions it can be a factor 2 higher depending on the collision configuration. It is also observed that the v3(pT) is higher for tip-to-tip and body-to-body configurations compared to other systems for the collision centrality studied.