"In Matlab you can concatenate arrays by saying "
Yes, and the square bracket concatenation operator works with all types of array, not just numeric ones. Lets try:
[1,2,pi] % concatenate scalars
C1 = {1,'cat'};
C2 = {2,'hat'};
[C1;C2] % concatenate cell arrays
T1 = cell2table(C1,'VariableNames',{'A','B'});
T2 = cell2table(C2,'VariableNames',{'A','B'});
[T1;T2] % concatenate tables
S1 = string(C1);
S2 = string(C2);
[S1;S2] % concatenate strings
... etc etc.
In contrast, using {} is not a concatenation operator, it creates a cell array. So when you used {a,'abc'} you told MATLAB to create a new cell array containing those arrays.
