Commenting out "\qquad" not the same as removing it

Question

If I use the code below the two images are stacked horizontally, but when I remove the %\qquad` the subfigures are stacked vertically. I'm using Kile editor on Linux CentOs. Any ideas?

\documentclass{article}
\usepackage{graphicx}
\usepackage{subcaption}

\begin{document}
 \begin{figure}[!h]

  \begin{subfigure}[c]{.7\textwidth}
    \includegraphics[width=\textwidth]{Image1.jpg}
    \caption{Image 1}
  \end{subfigure}
 %\qquad
  \begin{subfigure}[c]{.2\textwidth}
    \includegraphics[width=\textwidth]{Image2.jpg}
    \caption{Image 2}
  \end{subfigure}

 \end{figure}
\end{document}

Answer 1

subfigures are placed just like large letters, so to understand the positioning, think of replacing \begin{subfigure}...\end{subfigure} by X.

Then the cases you might consider are

1.

XX

two X with no space between.

2.

X X

two X with a space between

3.

X
X

The same output as 2, as a newline is the same as a space,

4.

X%
X

The same output as 1, as the newline/space has been commented out.

5. (your original)

X
\quad
X

two X with a space and and additional 1em space.

6.

X%
\quad
X

two X with 1em space between

7. (your original with \quad removed)

X

X

Two X in separate paragraphs, so vertically stacked.