Hello there! 

Greetings! 

EI stands for electronics and instrumentation and it primarily focussing on the principles and operations of measuring instruments used in the design and configuration of automated system. It is the basis of mechatronics and robotics engineering.
While EC stands for electronics and commuciaction enginnering .
EC  branch teaches Electronics and its applications in Communication both analog and digital, it mainly belong to electronnics with communication instruments and technology like bluetooth infrared bandwidth's etc!! satellite communication etc .

Thankyou