The most likely cause is different JPEG compression quality settings, not the color profile.

JPEG size depends heavily on the chosen quality/compression level. A file saved at very high quality (for example, around 99) can be much larger than one saved at a slightly lower setting (such as 91), even if the images look nearly identical. File size tends to increase disproportionately at the top end of JPEG quality.

Based on the community answer, your smaller file appears to be saved around quality 91, while the larger one is around quality 99. That alone can explain most of the size difference. Re-saving the larger file at quality 91 brought it much closer in size.

An embedded color profile usually adds only a relatively small amount of data, so it would not account for a multi-megabyte difference by itself. Likewise, the reported number of colors is not the main reason here.

So the short answer: the big size gap is primarily due to different JPEG quality/compression settings.