Difference between MQL4 and MQL5 ?

[Everistus Dike]

please can any body tell me the major difference between MQL4 and MQL5.

Programs written in MQL4 can it work in MT5, if not what is the cause? and vice versa

[Simon Gniadkowski]

There are many, many differences in the languages . . .

This will give you some ideas: https://www.mql5.com/en/articles/81 and here: https://www.mql5.com/en/articles/66