Wire Speed Changing

Hi everyone. Just 2 quick questions. Firstly is there a difference between a mag wire feed unit and a mig wire feed unit. I have a mag wire feed connected to my 3 phase mig plant. I noticed that when a pull the trigger on my torch i get the desired wire feed rate. then when i arc the torch for welding the speed is much quicker? is there 2 speeds? one when not welding and one when you are welding. Also i noticed that when i change the wire speed not the voltage the current increase and decreases? i thought the current does not change until you change the voltage. Can anyone help me with this? Thanks.

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yest there are some mig machines that have 2 speeds.

technically wire speed controls amperage/current.

but you need voltage too to make the metal transfer and melt efficiently.

anyone else want to chime in?