Outlined below are the differences between TEX and troff that I know from experience with the two languages most of which obtained while writing tr2tex. Most of them are advantages TEX has over troff.

There are actually more than one type of TEX, the most used ones are L^ATEXand plain TEX Troff can also be loaded with various macro packages to produce variations to plain troff. Also, ditroff (device independent troff) is becoming more and more the standard of troff. The following comparison is made mainly between L^ATEX and ms troff. It will be mentioned if in a particular case ditroff makes a difference.

• TEX is not system-dependent. Troff is a Unix tool.

• In Troff, tables and equations are handled by preprocessors while in TEX they are simultaneously processed with text.

• Troff's commands have to start at the beginning of the line and start with a dot. Equation symbols are recognized when delimited by space. All TEX commands, in math or non-math mode, start with a backslash and they don't have to be placed at the beginning of the line.

• TEX and L^ATEX commands are more verbose than troff's. This can be an advantage or disadvantage depending on the user.

• TEX processes boxes such as lines and paragraphs as one unit. This means it can distribute badness over that box. For example, when a spacing between two lines needs to be large, because a line has large symbols, it will slightly stretch the line spacing in other lines to make the large spacing not look too bad. This also makes it avoid orphan lines.

• The input to L^ATEX is a more structured document with scopes. It makes it easier to proofread. Troff's input is less structured.

• Some TEX drivers make it very easy to include prepared graphs with the text. Including graphs with troff's text is more difficult.

• Many fonts can be loaded in a TEX document (up to 32); in troff, the limit is 4 (ditroff does not have this restriction).

• Non-math macros are defined just like math macros in TEX. In troff, define is used for math definitions and .de is used for non-math macros. Troff's macros can be made up from anything while TEX macros cannot have non-letters which is a nuisance sometimes.

• There is no limit on the page size in TEX. The size is limited only by the output device. Troff's paper size is limited.

• TEX is interactive, while troff is not. However, not many people can benefit from this feature since they have to be skillful in answering its questions.

• TEX and L^ATEX give a l o n g ambiguous log file that does not exactly tell what the error is. Troff does not give error messages.

• L^ATEX automatically numbers equations and figures, etc. A powerful cross-referencing technique relieves the user from worrying about having the right sequence of equations' and figures' numbers. This feature is not available in troff.

• The documentation in the L^ATEX manual is excellent. Troff's documentation is scattered over many references. The documentation in the TEXBook is very technical and the average reader may find it unreadable.

• At hanauma, we have a previewer for TeX on the SUN, but don't have it for troff.