Html.Label - Just creates a label tag with whatever the string passed into the constructor is
Html.LabelFor - Creates a label for that specific property. This is strongly typed. By default, this will just do the name of the property (in the below example, it'll output MyProperty if that Display attribute wasn't there). Another benefit of this is you can set the display property in your model and that's what will be put here:
public class MyModel
{
[Display(Name="My property title")
public class MyProperty{get;set;}
}
In your view:
Html.LabelFor(x => x.MyProperty) //Outputs My property title
In the above, LabelFor will display <label for="MyProperty">My property title</label>. This works nicely so you can define in one place what the label for that property will be and have it show everywhere.