Difference Between A 1986 And 2014 1/10-Oz Gold Eagle

I've got a 1986 and a 2014 gold eagle (1/10oz) and I see differences in color, surface, letters, even thickness.

The 1986 is more yellow-gold, slightly thicker and has larger letters on pluribus / in god we trust. It's also more shiny.

The 2014 is dull looking, more copperish, thiner, smaller letters (pluribus unum / god we trust), and the surface is weird.

Diameter same, weight +0.03gr for the 86 but it also has some metal solder on its side.

Anyway here goes

http://s22.postimg.org/dg9q79mc1/2014_1.jpg
http://s22.postimg.org/95v2boh8x/2014_2.jpg
http://s22.postimg.org/bd3wdcbwx/2014_3.jpg

I searched around a bit, found a similar phenomenon here:

http://www.coinsusallecollection.co...ins%2011.jpg

...you can see that the 97 (copperish / small letters etc) is like my 2014, while the 98 is like my 86.

Any ideas if that's normal?