What is the difference between x265 & x264 video coding? Which is advantageous?

---->>>A) is h.264 and ---->>>B) is h.265
1)INTRODUCTION:
-->>A)MPEG 4 Part 10 AVC (Introduced in 2004).

-->>B)MPEG-H, HEVC, Part 2 (Approved in Jan 2013 ).

2) PROGRESSION:
-->>A)Successor to MPEG-2 Part .

-->>B)Successor to MPEG 4 AVC, H.264.

3) SPECIFICATION:
-->>A)Support Up to 4K (4,096×2,304)
             Supports up to 59.94 fps
             21 profiles ; 17 levels.

-->>B)Up to 8K UHDTV (8192×4320)
           -upports up to 300 fps
            3 approved profiles, draft for additional 5 ; 13 levels.

4) COMPRESSION MODEL:
-->>A)Hybrid spatial-temporal prediction model
         - Flexible partition of Macro Block (MB) , sub MB for motion estimation
         - Intra Prediction (extrapolate already decoded neighboring pixels for prediction)
         - Introduced multi-view extension
           9 directional modes for intra prediction
         - Macro Blocks structure with maximum size of 16x16
         - Entropy coding is CABAC and CAVLC.

-->>B)Enhanced Hybrid spatial-temporal prediction model
          - Flexible partitioning, introduces Coding Tree Units (Coding, Prediction and                               Transform Units -CU, PU, TU)
          - 35 directional modes for intra prediction
          - Superior parallel processing architecture, enhancements in multi-view coding                            extension
          - CTU supporting larger block structure (64x64) with more variable sub partition                        structures
          - Entropy coding is only CABAC.

5) DRAWBACKS:
-->>A)Unrealistic for UHD content delivery due to high bit rate requirements. Frame rate                  support restricted to 59.94.

-->>B)Computationally expensive (~ 300 % + ) due to larger prediction units and expensive              Motion Estimation (Intra prediction with more nodes, asymmetric partitions in Inter              Prediction).

6) KEY IMPROVEMENTS:
-->>A)- 40-50% bit rate reduction compared to MPEG-2
             - Led the growth of HD content delivery for Broadcast and Online.

-->>B)- 40-50% the bit rate reduction at the same visual quality compared to H.264
            - Potential to realize UHD, 2K, 4K for Broadcast and Online (OTT).
              This obove points will clarify you with both h.264 and h.265 , and according to me                   currently h.264 is over h.265.
Hope this helps you.
Thanks.