I’m sorry, “difficult” is the wrong choice of word.
“Effective Fall 2017, the College of Engineering will not accept change of college applications for any of the following: EECS major, EECS/MSE joint major, EECS/NE joint major.”
http://engineering.berkeley.edu/admissions/undergrad-admissions/change-college
Do you know the difference between BA CS (from L&S) and a BS CS (from EECS)?
Do a search for more.
See above.