Difference b/w EAS and EWS ?

What is the difference between EAS (Exchange ActiveSync) and EWS (Exchange Web Service)? 

Exchange ActiveSync is a protocol developed specifically to support mobile devices that are written to use the ActiveSync API. 

EWS is a collection of several different web service APIs to support a multitude of services. Some of these are: 
Outlook for MAC 
Availability 
Mailbox Replication Service Proxy 

Also, many third-party vendors will use the EWS APIs to develop their products as it gives a robust platform for accessing mailboxes as the mailbox owner. A prime example of this is many archiving solutions.