Difference Between vSphere 5.1 and vSphere 5.5

Features	vSphere 5.1	vSphere 5.5
Physical CPUs per host	160	320
Physical RAM per host	2  TB	4 TB
NUMA nodes per host	8	16
Maximum vCPUs per host	2048	4096
VMDK Size	2TB	62 TB
Max Size of Virtual RDM	2TB	62 TB
VM Hardware Version	9	10
40 GBps physical Adapter support	No	yes
ESXi Free version RAM limit	32 GB	unlimited
ESXi Free version maximum vSMP	8-way virtual SMP	8-way virtual SMP
16 GB fibre channel End-to-End support	Support to run these HBAs at 16Gb. However, there is no support for full, end-to-end 16Gb connectivity from host to array.	Yes
APP HA	No	Yes
vFlash Read Cache support	No	Yes
VMware VSAN support	No	Yes
Expanded v-GPU and G-GPU support	only NVIDIA	NVIDIA, AMD and Intel GPU
vCenter Server Appliance With  Embedded Database support upto	5 Hosts and 50 Virtual  Machines	100 Hosts and 3000 Virtual Machines
Microsoft Windows 2012 Cluster Support	No	Yes
PDL (Permanent Device Loss) AutoRemove	No	Intoduced in vSphere 5.5
Graphics acceleration support for Linux Guest OS	No	Yes
Hot-pluggable SSDPCIe devices	No	Yes
Support for Reliable Memory Technology	No	Yes
CPU C-state Enhancement	Host power management leveraged only the performance state (P-state), which kept the processor running at a lower frequency and voltage	Processor power state (C-state) also is used, providing additional power savings  and increased Performance
LSI SAS support for Oracle Solaris 11 OS	No	Yes
vSphere Big Data Extensions	No	Yes
SATA-based virtual device nodes via AHCI (Advanced Host Controller Interface) support	No	Yes (Support upto 120 devices per VM)
Improved LACP Support	one LACP group per distributed switch	Supports up to 64
Multiple point-in-time replicas	vSphere Replication kept only the most recent copy of a virtual machine	Version 5.5 can keep up to 24 historical snapshots