subfigure vs subcaptionbox

\documentclass{article}

\usepackage{graphicx,subcaption}

\begin{document}

\begin{figure}
  \centering
  \subcaptionbox{Figure 1 that is very wide and then some more text}{%
    \includegraphics[width=0.45\linewidth]{example-image-b}%
  }\quad
  \subcaptionbox{Figure 2}{%
    \includegraphics[width=0.45\linewidth]{example-image-c}%
  }

  \medskip

  \begin{subfigure}{.45\linewidth}
    \includegraphics[width=\linewidth]{example-image-b}%
    \caption{Figure 3 that is very wide and then some more text}
  \end{subfigure}\quad
  \begin{subfigure}{.45\linewidth}
    \includegraphics[width=\linewidth]{example-image-c}%
    \caption{Figure 4}
  \end{subfigure}

  \caption{A figure}
\end{figure}

\end{document}