Both have a 4 slots interface and each slot accepts a single item only, similar to a Crock Pot. In these, players must place Light Bulbs, Glow Berries (or their lesser variant) or Mushroom Spores for the lights to function. The lights also act like an Ice Box and slow down the spoilage of the light sources put inside. Once these perish, they will either be dropped on ground or vanish.
The Glowcap is a more advanced version of the Mushlight, having a more expensive recipe. It will, along with Light Bulbs and Glow Berries, accept Mushroom Spores, which make it glow in Red, Green or Blue depending on the spore. Additionally, by mixing multiple colors in a Glowcap, one can obtain other color tones besides of the former three, plus light bulbs, such as:
Purple- 1 Red Spores, 3 Blue Spore
Pink- 3 Light Bulbs, 1 Red Spore
Yellow- 2 Red Spores, 2 Green Spores
Orange- 3 Red Spores, 1 Green Spore
White- 1 of each spore type, leaving 1 slot empty.
Cyan- 2 Blue Spores, 2 Green Spores
The more spores of certain color added into the Glowcap, the stronger the color will be visible. Adding Light Bulbs will brighten the color.