Vmware ESXi : Well, this is the physical part of vSphere. The virtualization OS installed in in physical servers and bastracts the physical resources of the server and distributes them across VMs.
VMware vCenter : It is the vsphere centralised management software. It is essential for configuring and managing the full potential of vSphere say HA, DRS etc
vSphere client: A client software that lets users connect remotely to Vmware ESXi and vCenter
vSphere web client: A web interface that allows users to connect remotely to vCenter client or ESXi
vSphere SDKs: Provides standard interfaces for VMware and third party solution to access VMware vSphere
VMFS : A high performance cluster file systems for ESXi virtual machnes
vSphere virtual SMP: Enables single virtual machine to use multiple physical processors simultaneously
vMotion: Enables migration of virtual machines from one datastore to another without service interruption*
vSphere HA: If the host ESXi fails, the affected virtual machines are restarted on other available servers with spare compacity
vSphere DRS: Distributed resource scheduler balances the computing capacity across vSphere clusters. DPM (Dynamic power
Storage DRS: Allocates and balances storage capacity and I/O dynamically across colections of datastore. This includes management capabilities that minimise the risk of running out of space and risk of I/O bottlenecks that slow down the performance of virtual machines
vSphere FT: Provides continuous availability by protecting a virtual machine with a copy. When this feature is enabled for a virtual machine, a secondary copy of the original, or primary, virtual machine is created. All actions completed on the primary virtual machine are also applied to the secondary virtual machine. If the primary virtual machine becomes unavailable, the secondary machine becomes immediately active
vSphere Distributed switch: A virtual switch that can span multiple ESXi hosts, enabling significant reduction of on-going network maintenance activities and increasing network capacity. This increased efficiency enables virtual machines to maintain consistent network configuration as they migrate across multiple hosts.
Host profile: A feature that simplifies host configuration management through user-defined configuration policies. The host profile policies capture the blueprint of a known, validated host configuration and use this configuration to configure networking, storage, security, and other settings across multiple hosts. The host profile policies also monitor compliance to standard host configuration settings across the datacenter. Host profiles reduce the manual steps that are involved in configuring a host and can help maintain consistency and correctness across the datacenter.
Host profiles are also a component of vSphere Auto Deploy. The concept of an autodeployed host means that vCenter Server owns the entire host configuration and it is captured within a host profile.
Certain policies require user input to provide host-specific values. To support Auto Deploy for host profiles, an answer file is created that contains the definitions for those policies.
*vMotion is not supported across datacenters