Midjourney is a commercial image generation and transformation AI service. Similar services include:
- DALL-E 2 (Microsoft)
- Nightcafe
- Stable Diffusion (Open Source)
Midjourney is a somewhat opinionated AI and tends to try to create "art". It has a very high level of coherence, which means elements in the resulting images tend to have natural relationships with a low level of glitches and random weirdness. In my opinion, Midjourney has much higher quality "out of the box", trouncing the competition unless the user is quite advanced at effectively utilizing both positive and negative prompt particles.