Aladin,
It's a bit off topic from this thread. Excel requires you to explicitly declare array sizes, and many of the formulas are incompatible with arrays. For instance if you want to do a VLOOKUP an item C1 in a range A1:B50 that is not sorted, but the item you are looking up is in column A from column B, in excel you the solution I usually see is to use a CHOOSE formula.
So for excel the formula would be: =VLOOKUP(C1,CHOOSE({1,2},B1:B50,A1:A50),2,FALSE).
Where in Google Sheets you can do: =VLOOKUP(C1,{B1:B50,A1:A50},2,FALSE)
•Google sheets has additional array typeformulas FILTER, QUERY, SPLIT which are all very powerful -- in excel you are required to do these through utilites ( usually under data tab ).
•The arrays in Google Sheets are dynamic so you don't have to explicitly select the range.
•The error codes in google sheets are more useful and tell you what the exact problem is. ( for example Array could not be expanded because it would overwrite the data in cell B47)
•The ARRAYFORMULA formula in google sheets works the same as excel as hitting ctrl shift enter, and it intuitively allows for many regular formulas to be generalized ( not all formulas, for instance index match doesn't work well, but VLOOKUP doess )
• You can embed array formulas in the header and no longer worry about it. For instance if you have an invoice sheet that lists #OfUnits in column A, and Price in Column B, you can embed an array formula in Column C's header and it will automatically multiply the results from the first two columns ={"Total";FILTER(A2:A*B2:B,A2:A<>"",B2:B<>"")