I understand that some packages (like PSTricks) can't be used with pdflatex. Are there any other differences between these tools?
Can we say that pdflatex is better if we don't care about ps?
Some packages only work with direct PDF output, since they utilise features not available in PostScript, as mentioned by Dima.
Another difference stems from the fact that
pdftex are simply different programs, implemented independently. In particular, author Hàn Thế Thành implemented features in pdfTeX which help improve the document’s microtypography. Some of these features have since been implemented in
tex (the program, not the language), while others have remained exclusive to pdfTeX (although LuaTeX and XeLaTeX have also implemented some of them).
Here is a screenshot illustrating the difference (left: LaTeX, right: pdfLaTeX with microtype) – the example document was created with the help of the microtype package, which provides a simple interface to access the microtypography features:
[Taken from the TeXblog]
I think the only reasons to continue to use
Apart from those, I think that
pdflatex is effectively the default.
latex are typically the same program, but when it's invoked as
latex it defaults the value
\pdfoutput=0, rather than
\pdfoutput=1. If this is the case in your installation, you can use plain
\pdfoutput=1, amd get PDF output rather than DVI, and vice versa.)
You can use pstricks from pdflatex, by using a few tricks (all boils down to manual->automatic external invocation of latex&pstopdf to get pdf image of pstricks graphic which can then be picked up by pdflatex).
For beginners there are almost no difference. Once you get to advance usage you start to realise that special things need to be done to use Postscript constructs with pdftex (e.g. pstricks), but on the other hand pdftex engine gives you awesome stuff like pdf table of contents, pdf hyperlinks within document and URL to the web as well as generating pdf metadata, embedding movies / 3D objects, creating PDF-A ready documents for archiving and ability (with certain degrees of pain) to use TTF fonts.
Inverse search is a bit easier with latex. And dvi compilation & preview is much faster. But SyncTeX shows promise for awesome pdftex inverse and forward search.
If you don't use postscript stuff and care about creating high quality PDFs then pdflatex is preffered. But many people use both and have conditional compilation and macros in the preemble when using one or the other engine.
For beginners I would recommend pdflatex since most new users coming from WYSIWYG world of things do not know what dvi and ps are, but everyone nowadays is aware of PDF. After beginners stage it is an open-ended question which depends on particular needs with all engines having special features, advantages and disadvantages.
Major reason to use Latex is to be able to use tex4ht.
Tex4ht needs dvi files generated from latex, it does not need pdflatex.
Without Latex, tex4ht will not work.
And since the cloud and HTML and the web is the future of publication, and since Tex4ht is the only feasible way to convert latex file to HTML pages (the only practical link we have between tex and the cloud really), I would say this makes latex even more important.
If I have to be sent to a deserted island and have to choose between taking latex or pdflatex with me, I would pick latex so I can use tex4ht and be able to write to the cloud and generate HTML using it.
Roughly, LaTeX knows nothing besides EPS (though most things can be wrapped into EPS via fig/xfig/winfig),
pdflatex does all sorts of graphic (though not
pdfLaTeX does not work nice with
fancyhdr, among others.
With graphic, you will prefer pdfLaTeX, without graphics, latex is more likely to deal with "everything else".