Transmitted reference (TR) (Hoctor, R. and Tomlinson, H., Proc. IEEE Conf. on Ultra Wideband Systems and Technologies, p.265-9, 2002) and differential (DF) (Ho, M. et al., Proc. 55th IEEE Vehicular Technology Conf., vol.4, p.1896-1900, 2002) schemes are alternatives for ultra-wideband (UWB) communication systems. They both employ non-coherent autocorrelation receivers, circumventing problems of template signal design and multipath energy combining. Their receivers can also operate at different synchronization accuracy levels, being more robust to synchronization inaccuracy than coherent receivers. The BER performance of TR and DF receivers at different synchronization levels is derived. Comparisons of TR and DF schemes are made, and the tradeoff between performance and synchronization complexity for autocorrelation receivers is discussed. Simulations corroborate our findings.