Kernel Types
-generic kernel - this is the stock kernel that is provided by default in Ubuntu.
-preempt kernel - this kernel is based on the -generic kernel source tree but is built with different configurations (settings) to reduce latency. Also known as a soft real-time kernel.
-rt kernel - is based on the Ubuntu kernel source tree with Ingo Molnar maintained PREEMPT_RT patch applied to it. Also known as a hard real-time kernel.
-lowlatency kernel - very similar to the -preempt kernel and based on the -generic kernel source tree, but uses a more aggressive configuration to further reduce latency. Also known as a soft real-time kernel.
-realtime kernel - is based on the vanilla kernel source tree with Ingo Molnar maintained PREEMPT_RT patch applied to it. Also known as a hard real-time kernel.