The difference between brown and plum is subtle, depending on the lighting. I think you'd need to view both side by side in person, and relatively bright outdoor lighting, to be able to tell them apart right away.
Brown on the left, plum on the right - indoor lighting at Leffot:
Mine in brown, pic taken on a cloudy morning:
/****** Apparently I live on Instagram too - mainly timepieces, shoes, attire and the occasional cheeseburger. @no_frills_vc. ******/