And here's what it looked like in Mail on macOS. The difference is more subtle, but the text of [MAJOR METROPOLITAN AREA] is still smaller (capital letters are 25px instead of 28px).
Also one of them is Arial and the other is Helvetica. Now, I know what you're thinking -- normally when someone makes that distinction you know that you're dealing with some kind of font-hipster super-nerd. This is true. But when they're side by side, sometimes even normal people can tell them apart!
Here's an easy way to screw up like this on macOS:
- Compose an email in Mail.app.
- Format / Make Rich Text.
- Type stuff.
- Open Notes.app and copy stuff.
You will almost certainly get different fonts, because you didn't do "Paste and Match Style".
"Make Plain Text" also works, because nobody needs to see the damned fonts in your damned email in the first place (sorry not sorry).
And it's not just Apple; the Google and MICROS~1 tool sets all fuck up in nearly identical ways. Besides the highly visible breadcrumbs that they reveal through this kind of font fuckery, view source also reveals many other edits. You tend to get a new DIV or SPAN every time you paste something or join paragraphs, and that reveals clues about your editing process, information that you probably didn't intend the recipient to have.
I guess it's unsurprising that the people writing these rich-text editors screw up in this way -- it's probably inconceivable to them to be concerned about the on-the-wire representation of the data they are emitting, beyond whether it displays correctly for them personally. For other examples of this lack of craftsmanship just look at how pathetically every mail reader encodes quoted-printable -- a format intentionally designed to be readable by humans in the raw, but now universally treated as a binary blob. Or the criminally incompetent manner in which they all convert HTML to text/plain in multipart/alternative. Or, gestures wildly at the entirety of XML and JSON.
But the font size changes are surprising, because it's so obvious. It makes you look like you screwed up. Surely people have complained about this. And by "people" I mean "people who matter", you know, wealthy clients.