According to apple.com, the iPhone 11 has a 6.1 inch Liquid Retina HD display LCD multi-touch display. The Samsung Galaxy S20 has a 6.2-inch Dynamic AMOLED display with a 120Hz refresh rate, instead of the 60Hz that you get with the iPhone 11. The iPhone has 326 ppi, but the S20 has 563 ppi. The S20 clearly has a better display, but it will use more battery life if the 120hz setting is used.
Both have an IP68 resistance level, but according to apple.com, the iPhone 11 can be submerged to up to 6.5 foot for 30 minutes, whereas the S20 can only be submerged to 3 foot for 30 minutes.
The Samsung Galaxy S20 has a Snapdragon 864 from Qualcomm and the iPhone 11 has the proprietary A13 Bionic chip with the third generation neural engine. According to cnet.com, both phones are quick for everyday tasks, but on the paper the iPhone 11 is faster.
According to apple.com, the iPhone 11 has has a 12 MP wide camera and a 12 MP ultra wide camera. It has a 2x optical zoom out and 5x digital zoom. The iPhone also has Deep Fusion, which increases detail in photos. On the S20, you can take up to 63 MP photos. According to cnet.com, the S20 has a triple camera set up, including a telephoto lens, which means that you can zoom in 30x; however, according to review, you wouldn't want to go past 10x. With the iPhone you can record in 4K, but on S20, you can record in an impressive 8K, but this well eat up storage.
If you just want to take great photos and videos without changing settings, the iPhone is the best choice as the process is less complex, but if you know the basics of photography and want to change settings to use features, then the S20 is the best choice.
The S20 has a optical fingerprint sensor built into the display, so that you can just press your finger onto the screen to unlock it. It also has facial recognition, but it isn't as sophisticated as the system on the iPhone that uses Face ID. Face ID utilises three modules, a dot projector that projects infrared dots onto one's face and then a module called the flood illuminator reads the dots and creates a 3D facial map of one's face. It also has an infrared camera to take a picture of the face. All of this combined means that, according to apple.com, the chance of a random person unlocking an iPhone is 1 in 1,000,000, compared with the 1 in 50,000 chance with Touch ID.
The iPhone has a maximum capacity of 512 GB. The S20 has a maximum of only 128 GB.
The Samsung Galaxy S20 starts at £899 and the iPhone 11 starts at £729.