The short answer is hard enamel pins are polished flat whereas soft enamel has recessed enamel. Daymare pins are hard enamel pins - why? They are so shiny!
One is not better than the other - it is all about personal preference!
Soft enamel pins are really desirable as you can achieve smaller details in the design. Enamel colors are added into recessed areas of the metal parameters and the enamel dries just below the metal die line. This results in a dimensional and “bumpy” feeling to the enamel pin.
For this process the enamel colors are added above the metal line and then polished flat to the same level. Each enamel color is baked separately which makes this process more costly. The pin is polished after every color as well making it super shiny and smooth. In the jewelry world this type of pin process is known as cloisonne which is a high-end jewelry standard.
Fun fact! Daymare’s very first pin was a soft enamel pin. Every pin created afterwards has been hard enamel.