There's no such thing as "symbian 60"
or "symbian 40". What you're talking
about is S60, a Symbian OS based
platform, and Series 40, a Java platform
running on top of Nokia OS.
S60 phones are smarphones, thus they
are more advanced (and more
expensive) than the Series 40 ones.
There are many features which are
better and bigger on the S60
smartphones.
As for what the dictionaries are
concerned, the share size of them could
be different, i.e. number of words
known. S60 can handle more words
than an Series 40 device (more
memory available)
Aside from that, the S60 phones are
also capable of multitasking.