# Difference between measures of \vskip in plain TeX and LaTeX

I have recently heard the argument that "plain TeX is superior to LaTeX because TeX gets the measures right". The example given was that a \vskip 2 cm, when run in tex, would measure exactly 2 cm from baseline to baseline, whereas the same running latex would result in 2 cm from baseline to topline.

TeX MWE:

One line.
\vskip 2cm
One line.
\vskip 2cm
One line.
\vskip 2cm
\bye

LaTeX MWE:

\documentclass{article}
\usepackage{lineno}

\begin{document}

\linenumbers

One line.
\vskip 2cm
One line.
\vskip 2cm
One line.
\vskip 2cm

\end{document}

What makes the result different?

-
\vspace doesn't start a new paragraph, while \vskip does, so this example is not good. –  egreg Apr 15 at 23:08
You should probably take a look at the definition of \vspace (and \@vspace) in latex.ltx as a start. –  Werner Apr 15 at 23:08
@egreg, you're right, I edited the MWE. –  Joseph Apr 15 at 23:09
You should almost always have a blank line before \vspace (then you'll get the result that you imply that you want) (and don't believe everything you hear, the argument that you quote makes a false conclusion from a false premise) –  David Carlisle Apr 15 at 23:10
You have changed the latex example to use vskip, so now I don't understand the question at all, vskip is identical in latex and plain tex (it is a tex primitive) –  David Carlisle Apr 15 at 23:11

This is what I get from the Plain TeX file and the corresponding LaTeX file; I have used pdfcrop to crop the PDF and used the same parameters for converting to PNG.

\nopagenumbers
One line.
\vskip 2cm
One line.
\vskip 2cm
One line.
\bye

## LaTeX file

\documentclass{article}
\pagestyle{empty}
\begin{document}

One line.

\vspace{2cm}
One line.

\vspace{2cm}
One line.

\end{document}

Left is Plain, right is LaTeX

Conclusion: what you heard is not true.