Before going forward to talk on Difference between view Access points and View security servers lets discuss a bit about the roles of security servers in a horizon view environment.
Well security server play an important role when we talk about availability of view services over internet.
As we are aware we need connection servers to be part of domain and its never a best practice to keep your domain joined components into DMZ.
To solve above problem statement We have Horizon View Security Servers that take care the requests coming for View services , They reside into the DMZ network which is open for internet requests and can communicate to back end horizon view connection servers in trusted Network on specific ports
SO View security servers act as proxy for connection coming from internet and the back end horizon view connection servers.
their are two possible communication configuration . With Secure Gateway (recommended)or Without Secure Gateway.
How Security Servers configured : There is always a one to one mapping when we need to deploy security servers for a view instance.
Concern point : in this case we are having mapping between security servers and if one security server fails we may not be able to use associated connection server for any connection , so their is dependency.
What is Access Point or Security Gateway :
Well Access point is a virtual appliance designed to allow secure remote access to horizon view desktops from Internet. Its a DMZ component same as horizon view security server but with different way for working.
as there was one to one mapping in case of view security servers , Access points work differently. As explained in below diagram, we can point them to a vip which has view connection servers in back end.
so its not creating any dependencies even if one of my Access point goes down both connectors still will take care of the requests, it involves active load balancer participation.
More over difference in basic functionalities Unified gateway (Access points) has less security risks as this is hardened for security risks compare to security servers having Windows operating system.
in addition VMware Unified Access Gateway can be the internet facing layer for all VMware End User computing Products like Airwatch MDM, Horizon View, and VIDM.
this can work in combination with F5 and take care all DMZ functionalities Making access to EUC services more secure.