1)galvanic series is for both elements and alloys whereas emf series is only for elements

2)galvanic series tells about relative tendencies of corrosion whereas emf series tells about relative tendencies of displacement

copper is higher in galvanic series than steel.hence when steel bolt is attached to copper equipment the copper being higher in galvanic series acts as anode getting corroded and steel being lees in galvanic series acts as cathode getting protected.

copper equipment gets corroded when steel bolt is attached to it.

There really isn't a most stable metal on the galvanic series. The series works with pairs of metals having differences is voltage potentials, very much like a battery made of two metals placed in an acid solution. Dissimilar metals together, such as copper and iron, will create a galvanic cell. On the galvanic chart, metals are arranged according to their galvanic potential voltages, with the ones at the far ends most likely to be unstable. This is manifest in the corrosion of one metal to deposit onto the other metal, similar to a metal plating situation. The closer any two metals are on the series, the more stable they are. The further they are apart, the more likely one is to corrode. This occurs often in waterworks and plumbing with metallic pipes. Others are invited to check my verbiage on the description.

A voltaic battery is also known as a voltaic pile, which is a set (or pile) of galvanic cells linked together in series to create a larger voltage than could be generated by a single galvanic cell. Therefore a voltaic cell would simply be one element of the pile which is also one galvanic cell.

Each metal when placed into an electrolyte, water, seawater, soil or any other good electrolyte, has an electric potential. This potential is different for every metal.

The galvanic series is a list of this potential arranged from the most "active",lower potential to the most "noble", higher potential.

The terms "noble" and "active" means that when two metal are connected the most "active", with the lower potential will corrode, while the metal with the higher potential, the "noble" material will not corrode.

The galvanic series, the potentials, are different in different electrolyte.