EN wikipedia says "pearl barley" is barley that has been processed to remove its outer hull.
  https://en.wikipedia.org/wiki/Pearl_barley

JA wikipedia says もち麦 is an inherently glutinous type of barley. Nothing about processing.
  https://ja.wikipedia.org/wiki/オオムギ
  また、上記の品種はすべてうるち性であるが、日本を含む東アジアにはもち性のオオムギも存在する。もち麦は日本ではもち米の代替として西日本中心に栽培され、団子などがこれで作られた。 

Daijirin also doesn't say anything about processing.

I see a lot of cooking websites refer to it as "mochi mugi" and "Japanese pearl barley," though.
  https://www.justonecookbook.com/mochi-mugi/
  Mochi Mugi (もち麦), or Japanese pearl barley, ...

  https://umami-insider.store/products/japanese-pearl-barley-mochi-mugi
  Japanese Pearl Barley (Mochi Mugi)


〈餅／糯／もち／モチ〉〈麦／むぎ／ムギ〉

Google N-gram Corpus Counts
╭─ーーーー─┬───────┬───────╮
│ もち麦　 │ 7,957 │ 69.3% │
│ モチ麦　 │   329 │  2.9% │
│ 餅麦　　 │   156 │  1.4% │ - (I think this is irregular)
│ 糯麦　　 │     0 │  0.0% │ - (daijirin)
│ もちむぎ │ 2,920 │ 25.4% │
│ モチムギ │    81 │  0.7% │
│ モチむぎ │    36 │  0.3% │
╰─ーーーー─┴───────┴───────╯

I'm not sure about "pearl barley," but I guess it's okay with the other glosses.

@@ -5,0 +6,12 @@
+</k_ele>
+<k_ele>
+<keb>糯麦</keb>
+<ke_inf>&rK;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>モチ麦</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
+<k_ele>
+<keb>餅麦</keb>
+<ke_inf>&sK;</ke_inf>
@@ -12 +24,3 @@
-<gloss>pearl barley</gloss>
+<gloss>Japanese pearl barley</gloss>
+<gloss>glutinous barley</gloss>
+<gloss>mochi mugi</gloss>