The 500EX has a smaller guide number than YN-568Ex (53 vs 58). The 500EX is using the legacy Prontor-Compur (PC) type rather than the 568EX 2.5mm sub-mini. The 500Ex is smaller than the YN-568Ex. Suitable for: Wirelss TTL Slave mode(both version): Canon 5DIII 7D 60D 600D 650D, Yongnuo ST-E2, Canon 580EX II Nikon SB-900, SB-800, SB-700, Commander SU-800, Camera with CLS i-TTL system:D4, D3x, D3s, D3, D2x, D700, D300s, D300, D200, D7000, D90, D80 Hot shoe E-TTL mode(Canon Version): Canon 1Dx, 1Ds series, 1D series, 5DIII, 5DII, 5D, 7D, 60D, 50D, 40D, 30D, 20D, 650D/T4i, 600D/T3i, 550D/T2i, 500D/T1i, 450D/Xsi, 400D/Xti, 350D, 1100D, 1000D