Why same company StateStreet is having two ETFs, GLDM (ER=0.1) and GLD (ER+0.4) ?

I see same company floating two gold ETFs, as given in title, with different ER. Above all, I see volume of GLD is double of volume of GLDM and price of GLD is 5x of GLDM.

I do not understand why two same commodity etfs and the higher price ETF has higher volume.

Is there any benefit or coverage higher in GLD than GLDM and why GLD is attractive than GLDM (based on volume inspite of ER high)?