Thank you, Teacher 862311's answer, but I am still confused.
I may have to switch to another department within the same employer prior to 180 days of pending I-485. The new job duties will be different from those listed my PERM and I-140, but both jobs have the same occupational classification code (Department of Labor's Code), the same position title, and the same level of salary.
(1) Will I be considered to change my employer?
(2) Will new job be considered to be the same or similar occpuational classification? (It is very hard to understand the definition of Same/similar Job. Dose same/similar job weigh job duties more than job classification?)
(3) will my current H1B still be valid? if not, will it be safer to use EAD than to file a new H1B?
(4) Does law say my employer must cancel my current H1B?
I sincerely appreciate your insight.