Applying css styles based on html element sequence - through a .css file

I am applying styles to my html elements from a style
sheet.

I want to know what is the difference
between

//No comma
            seperation
.elementSpace tbody tr td input label{ 
 margin-left:
            0.5em;
}

and

//comma
            seperation between input and label
.elementSpace tbody tr td input,
            label{

 margin-left:
            0.5em;
}