Is these two regex checker are different /S+/g (capital “S”) and /s+/g?

    function wordCount( val ){
     var wom = val.match(/S+/g);
     return {
     charactersNoSpaces : val.replace(/s+/g, '').length,
     characters : val.length,
     words : wom ? wom.length : 0,
     lines : val.split(/r*n/).length
     };
    }

I am just asking, they both behaving totally opposite.