Lip balm is used to moisturize lips. The type JTG has created contains a combination of plant based oils and waxes to delivery a diverse range of nutrients, which might be particularly helpful to those who have diets that require careful monitoring of iron, zinc, and B vitamins since deficiencies of those vitamins can sometimes leave lips more prone to peeling.
Lip scrub is an exfoliating product designed to help release dead skin cells clinging to your lips. The biggest reason why someone might want to do this is because dead cells are not capable of absorbing moisturizer/lip balm and passing that moisture down into deeper layers of skin. In fact, dead cells cause quite the opposite effect: moisturizing products applied to them act kind of like glue, sticking them down to the surface, blocking moisturizers for getting where they needs to go. As such, gently exfoliating on a regular basis helps to reveal newer layers of skin more capable of absorbing moisture, thereby making your moisturizing efforts more effective.
Another reason people like to exfoliate their lips is because darker shades of lipstick/stain need a smooth, even surface in order to deliver a consistent layer of pigment. So if you're tired of applying lipstick only to rub it off with a tissue then try again, try exfoliating first, then applying lip balm (or lip primer), and then your vibrant hues!
All in all, you can use lip balm without lip scrub if you want, but I don't recommend using lip scrub without lip balm. JTG's version contains both an emoilient and a humectant in addition to the sugar, but not enough of either to last nearly as long as the lip balm formulations 
Looking for lip balm? Find it here: https://justthegoods.net/products/vegan-lip-balm
Looking for lip scrub? Find it here: https://justthegoods.net/products/vegan-lip-scrub