If you are a bit unsure what the various Topic Icons mean (when browsing a forum for interesting or relevant posts), then
the following link contains a post that lists and explains them, though they're not all necessarily implemented on every phpBB forum.
Go to the last post on this link and you should see the images and descriptions of the phpBB topic icons:-
https://www.phpbb.com/community/viewtop ... 2&start=15" onclick="window.open(this.href);return false;
FYI -Topic icons (meaning)
FYI -Topic icons (meaning)
Don' t forget the 80-90 Wikipedia has a fair bit of help, info and a smattering of wisdom in it 
Donald 1.9TD Syncro Doka / Tyger Syncro Kastenwagen
Syncronaut

Donald 1.9TD Syncro Doka / Tyger Syncro Kastenwagen
Syncronaut