Apply map is that you get data from an QVD file, it is more or less Vlookup in Excel. I use it if i want to put an extra field from a qvd to another qvd file.
An inline table is just an table that you could add and write your own table.
I am using the inline table as a VLOOKUP with QVD tables in my data model, and it's working fine. However if I understand what you are saying, you use the ApplyMap to ADD fields from an existing QVD to another table vs creating a whole new table in the data model via an Inline...? Correct me if I did not understand...
Mapping isn't restricted to qvd-loads else could be applied by each kind of loads. Further it's not only usable to add fields else also to check and manipulate data. It's simple, fast and without risks to change the number of records - as joins would do. So a lot of possibilities ...
With applymap, you can specify a default value which will be used if the mapping table does not contain a matching value.
So if there is a chance that the field you wanted to map at a a later time may have values that are unknown to you now (and your lookup table is not automatically updated as well), then applymap is better.
