# Difference in the three methods for unnumbered equation [duplicate]

What is the (subtle) difference between the three ways to typeset unnumbered equations (if any)?

The first is the plain tex,

$$E = mc^2$$


The second is the LaTeX

$E = mc^2$


And the third is the AMS,

\begin{equation*}
E = mc^2
\end{equation*}


As far as I can tell, the end results are almost the same. If there's any difference, most likely in the spacing around the formulas. But I cannot find any concrete reference for the later two.

• With \usepackage{amsmath}, methods 2 and 3 are exactly the same. – egreg Jun 20 '16 at 9:50