First things first - underwater photography is not easy; a new diver has to control their buoyancy, manage their gear, maintain situational awareness of their dive group and environmental hazards, all while keeping a proper breath rhythm in order to minimize air consumption. Adding a camera to the mix significantly increases task loading and can pose a hazard to the diver if their buoyancy and breath rate control haven't been practiced to the point where they are done subconsciously.
That said, Micro 2.0 is permanently sealed and doesn't need a housing to dive. However, its feature set is quite limited - most glaringly, only automatic mode operation, no ability to shoot in RAW mode, and no way to trigger an external flash, so while it is a fine choice for a beginner, it can become limiting to someone looking to advance their underwater photography skills.
DC2000 is also waterproof, but only to 18m depth - taking it deeper requires its bundled housing, which increases weight and bulk. Whereas a Micro 2.0 can easily fit into a BCD pocket, a housed DC2000 would be a more difficult fit. On the other hand, it has a full set of controls, it can trigger strobes via fiber optic cables, it has a high-quality 1" sensor (same as the Sony RX100 III camera) behind a good lens, and it can shoot in RAW mode, albeit with long (several seconds) intervals between shots. It has the potential to deliver much higher quality results than the Micro 2.0, but extracting that potential requires skill and additional investment - for example, the Sea Dragon Duo X2 strobe set costs as much as the camera with its housing.
I would say that the Micro 2.0 is a better choice for the occasional vacation diver looking to snap a picture every now and then. DC2000 is a more serious tool for someone looking to pursue underwater photography as a hobby and willing to part with the significant amounts of money that it generally requires. Note that SeaLife is far from the only choice in underwater photography - Olympus TG series cameras are generally quite well regarded, particularly for macro photography, and most underwater photographers use regular land cameras in waterproof housings. Keep in mind that supposedly waterproof cameras like SeaLife DC2000, Olympus TG series, Nikon AW series, etc, depend on a thin and fragile o-ring to keep water out of the camera's vulnerable innards, and can flood just as easily as - some would even say more so than - any housing.
