Surfaces & depth
iOS: conventionally uses a blur effect to indicate depth.
Android: focus on a considered use of elevated surfaces and shadows.
Interaction & motion (touch feedback styles)
iOS: color change or dimming
Android: ripple and rise. This magnetic reaction is authentically digital.
iOS: pt (Points), 1x: 1pt=1px; 2x:1pt= 2px
Android: dp (Density-Independent pixels) (1dp = 1px @ 1x (where 1x on Android is 160dpi)
DPI (Dots per inch)
Android: elements is in multiples of 8dp; The standard keylines for phones are 16dp and 72dp
iOS: Helvetica Neue, PingFang SC, San Francisco
Android: Roboto; baseline grid of 4dp, so line heights should be 20dp, 24dp, 32dp, 36dp
Apps vs. Activities
Android: Activities- intent; Their ability to work across apps.
iOS: Physical buttons - Home & Overview
Android: Physical buttons - The system Back button, Home, and often Overview
iOS: Navigation Bar (Top), Tab Bar (Bottom)
Android: Physical buttons - The system Back button, Home, and often Overview; Navigation - the top tab bar, A navigation drawer
Quick Overview for iOS: https://designcode.io/iosdesign-guidelines