what is the meaning of "type loop" in the asoundrc file?

Question

I am new to ALSA and its userspace configuration. I saw one pcm device in my asoundrc like below

pcm.myalsadev{
    type loop
    device 0
    ipc_perm 0660
    ipc_gid audio
    subdevice 0
    rate 16000
    channels 1
    format S16_LE
}

What is the meaning of plug-in type "loop" ? I checked this document but i cant see any expiation.

I know what is the meaning of the below configuration. Here they are using snd-aloop Linux driver to implement a loopback device, and it is same as hw:Loopback,0,0. Please correct if my understanding is wrong.

pcm.myDev{
    type hw
    card "Loopback"
    device 0
    subdevice 0
    rate 16000
    channels 2
    format S16_LE
}

is both the configuration are same and just an another way of representation ? Thanks in advance!