The iPad mini 4 and iPad mini (5th generation) both have a 7.9-inch Retina display with a resolution of 2048x1536 at 326 ppi. These displays feature LED backlighting with IPS technology, are fully laminated, and have an anti-reflective coating. The iPad mini (5th generation) also includes True Tone technology, which the iPad mini 4 lacks.
The iPad mini (6th generation) has a slightly larger 8.3-inch Liquid Retina display with a resolution of 2266x1488 at 326 ppi. This display also features LED backlighting with IPS technology, an anti-reflective coating, P3 wide color, and True Tone technology, offering improved color accuracy and a more immersive viewing experience.

The iPad mini 4 is powered by the A8 chip, which is a much older processor, providing basic performance suitable for general tasks.
The iPad mini (5th generation) is a significant upgrade, featuring the A12 Bionic chip with a 6-core CPU, 4-core GPU, and an 8-core Neural Engine, offering much faster performance and better efficiency.
The iPad mini (6th generation) is equipped with the A15 Bionic chip, which includes a 6-core CPU, 5-core GPU, and a 16-core Neural Engine. This chip provides the best performance among the three, supporting more demanding applications and offering enhanced machine learning capabilities.

The iPad mini 4 and iPad mini (5th generation) both have an 8MP Wide rear camera with an f/2.4 aperture, capable of recording 1080p HD video. The front camera on the iPad mini 4 is a 1.2MP FaceTime HD camera, while the iPad mini (5th generation) improves on this with a 7MP FaceTime HD camera.
The iPad mini (6th generation) offers the most advanced camera setup. It features a 12MP Wide rear camera with an f/1.8 aperture, capable of 4K video recording, and a 12MP Ultra Wide front camera with Center Stage, which keeps you in frame during video calls.

The iPad mini 4 and iPad mini (5th generation) both use the older Lightning connector for charging and data transfer. They support Wi-Fi 802.11ac and 4G LTE cellular connectivity.
The iPad mini (6th generation) uses a more modern USB-C connector, providing faster data transfer speeds and more versatile connectivity options. It also supports Wi-Fi 6, offering faster wireless performance, and 5G cellular connectivity, which allows for significantly faster mobile data speeds.

The iPad mini 4 does not support any Apple Pencil model, limiting its use for tasks like note-taking or drawing.
The iPad mini (5th generation) supports the 1st generation Apple Pencil, allowing users to take notes, draw, and interact with the device more creatively.
The iPad mini (6th generation) supports the 2nd generation Apple Pencil, which offers wireless pairing and charging, and attaches magnetically to the side of the iPad. This model provides a more seamless and integrated experience for artists and note-takers.