LOOKUP vs. VLOOKUP
Now LOOKUP and VLOOKUP are two worksheet functions which do a similar task of matching values and providing outputs but both are different. The difference lies in the working and the formula however both will perform the same search function. The key lies in understanding how the vector and the formula works in both the cases and how are the values returned when the function is executed.
LOOKUP Function: The syntax and vector of LOOKUP function will search for a matching value either horizontally or vertically in a given range of values specified and will return a matching value as per the second range supplied. However it is limited to a single column or row to hold the value returned. In this way it is different from VLOOKUP.
VLOOKUP Function: The syntax and vector of VLOOKUP function will search for a matching value in the first column of a range of cells and will give a value from the same row in the column which was specified by you in the range.
The main differences can be summarized as below:
1. LOOKUP is essentially only limited to a single row or column. You cannot have a multiple column range like in VLOOKUP. So basically LOOKUP will have a single row or range to lookup values and single row or range to hold the values returned. On the contrary VLOOKUP can have multiple column ranges, first the lookup column range and then the return ranges which can be specified in the parameters
2. VLOOKUP can also be called as vertical lookup as it can only run its search through columns. LOOKUP will automatically decide whether it will run the search horizontally or vertically and it cannot be specified.
3. VLOOKUP may find an exact match on sorted data or an approximated match on unsorted data however LOOKUP cannot handle unsorted data.