Conventional manufacturing methods face challenges with hard, brittle, or thermally sensitive materials. Abrasive Water Jet (AWJ) methods offer advantages when cutting those high-performance materials. However, milling with AWJ requires refinement to gain comprehensive knowledge of the process design. This study explores an experimental comparison of commonly used AWJ and an injection-type Abrasive Slurry Jet (iASJ). The gaseous phase in the jet tool can be minimised using iASJ. Because it uses a regular AWJ system, the iASJ allows a direct comparison of the results. Preliminary investigations focused on optimising slurry jet stability, while the central experiments studied the influence of the jet's phase composition on the erosion process. Here, a dense-sintered technical ceramic made of zirconia was used. Moreover, the study suggests that the absence of air suppresses high-frequency droplet erosion, minimising material outbreaks of brittle-hard materials.