As an expert in skincare and clean beauty, I can provide some insights into the differences between polygel and builder gel for nails.

Polygel and builder gel are both popular options for nail enhancements, but they have some distinct characteristics that set them apart.

1. Composition:
- Polygel: Polygel is a hybrid product that combines the qualities of both acrylic and gel. It typically consists of a combination of acrylic powder and gel. Polygel is often odorless and does not require the use of monomers or a UV/LED lamp for curing.
- Builder Gel: Builder gel is a type of gel that is specifically designed for building and sculpting nail extensions. It is typically made up of a gel-like substance that requires curing under a UV/LED lamp to harden.

2. Application:
- Polygel: Polygel is applied using a brush and spatula. It is usually squeezed out of a tube onto the nail and then shaped and molded with a brush to create the desired nail extension or enhancement.
- Builder Gel: Builder gel is typically applied with a brush and is built up in layers to create the desired nail shape and length. Each layer of builder gel is cured under a UV/LED lamp before applying the next layer.

3. Strength and Durability:
- Polygel: Polygel is known for its strength and durability. It offers a balance between the flexibility of gel and the strength of acrylic, making it less prone to breakage or chipping.
- Builder Gel: Builder gel is also known for its strength and durability. It creates a strong bond with the natural nail, providing a solid foundation for nail extensions. However, it can be more prone to breakage or chipping compared to polygel.

4. Removal:
- Polygel: Polygel can be easily removed by soaking the nails in acetone for a certain period of time. The polygel will start to dissolve, allowing for easy removal.
- Builder Gel: Builder gel usually requires filing or buffing to remove the majority of the gel, followed by soaking the nails in acetone to remove any remaining residue.

Ultimately, the choice between polygel and builder gel depends on personal preference and the desired outcome. Polygel is often favored for its ease of use, strength, and durability, while builder gel is popular for its versatility in creating custom nail shapes and extensions. It's important to note that both products should be applied and removed by a trained professional to ensure the best results and to minimize any potential damage to the natural nails.