R help - Jan 2015 - foreign:::writeForeignSPSS vs. write.foreign(df, datafile, codefile, package='spss')

Hello:
I discovered recently that the function foreign:::writeForeignSPSS allows for
variable names longer than 8 characters and has an additional argument varnames.
Neither of these capabilities exist with write.foreign. But according to the
help file for write.foreign it seems that the latter actually somehow calls the
former.  Am I reading this wrong? Can someone explain the difference between the
two functions?
Thanks.
Yours, Simon Kiss