Whining noise from the rear end, is this the differential?

[primitivoconner]

There's a whining noise coming from the rear of my Wrangler that gets louder with speed, and it's been getting more noticeable over the past few weeks. I've read that this can be a differential issue, which sounds expensive, but I'm hoping it's something simpler like a wheel bearing. I came across https://jeepservicemussafah.ae/ar/differential-repair/ while looking into it, but I'd rather hear from owners who've dealt with this. How do you tell the difference between a differential whine and a bearing noise? And if it is the diff, is it usually a rebuild or a replacement? I'd rather understand what I'm dealing with before I take it in, because I don't want to be quoted for a full rebuild if it's something cheaper.