The differences:
- With SEEK you can search with descending order ( for found the bottom ),
SEEK() have not this possibility.
- With SEEK() you can use the a field reference without the alias, with SEEK you cannot do this

* table1  id
* table2  id

select table1
SEEK id IN table2  && is SEEK table2.id IN table2
SEEK(id,'Table2')  && is SEEK(table1.id,'Table2')

When they use only the workarea with names of alias random, this becomes important.