Although the context is different, this is fundamentally a question of the difference in compression levels. ImageMagick identifies them as 81 and 95 — that's not a standard number, but it's generally true that 95 is "pretty high quality" and 81 is "medium-low quality". The issue of RAW vs. JPEG is a red herring here; it just happens that the embedded preview uses high compression by default. You can probably get the other , separate JPEG to be similarly compressed by changing your camera's settings.
So, then, this is really basically the same as Is it worth using Pentax's Premium JPEG quality setting? (whether or not you are using Pentax).
From my answer there:
where the low-quality (RAW preview) image is probably somewhere around the level of ★, while your separate "95" JPEG is probably like ★★★ (or maybe ★★).
My guess is that either:
A. Your subjects happen to be friendly compression and don't show significant artifacts; or
B. You're not looking closely enough. (What are jpeg artifacts and what can be done about them? will help you recognize what to look for).
If you decide you're happy with the results (for example, if you're really only going to be looking at them at that "macroscopic" scale you mention), and you keep the RAW images as a fallback, using the lower quality JPEGs is just fine. Just be aware that some scenes — like this high contrast red vs. blue — will be worse than others. For some situations, as my previous post suggests, you may want even higher-quality JPEGs.
Also, if you ever edit and re-save the JPEG, the degradation will be much worse (while it's almost negligible when working with 99- or 100-quality images).