What is the difference between Unified Communications and VoIP?

VoIP is one facility of the Unified Communications which include: VoIP, Video conference,... etc

in the past voice, data, and video each of these services has its own infrastructure network and it was difficult to integrate them. but now with high bandwidth it becomes easy.now cisco goal is " unified communication ". you can get voice, data and video on the same network infrastructure. 

in our daily communication we send chat messages, sms, emails, fax, phone calls, PABX calls, make video calls, send instagrams, post letters and alot more. Unified Communication is a process in which we integrate all above mentioned services in such a way thay they become part of a system. 

VoIP is a technology which is used to integrate few of mentioned above services. I have completed a CISCO based UCS project few months back and had hands on experience. drop me an email if further help needed.

voip is voice over ip, this is the transformation of the analogue voice to ip packets and use ip networks to make calls

unified communication is using the same ip network for data, voip and video (same cables, routers, switches, or access points ...) instead of using seperat netword for each service

we can say that voip is technology while UC is a group of technologies including voip.

Voip is a component of unified communication which consisted of Voip Video conferencing, tele-presence and messaging over IP networks 

VOIP - Transmission of Voice & Multimedia over IP.UC - Encompasses all forms of communications (IM, Video Chat, VOIP, IPTV etc.) over the network. #AspectSoftware