We have
$$CHINA=CHILE+3\implies NA=LE+3$$
$$ALGERIA=NIGERIA+2\implies AL=NI+2$$
Putting these together gives
$$A+A=E+I+5$$
meaning that $E+I$ is odd. This gives the idea of letting one vertical or horizontal stroke count for $1$, and $2$ for a slanted stroke, then $N=1+2+1$, $I=1$, $A=2+2+1$, and all equations are satisfied.
Now
ICELAND vs IRELAND means that we need to compare C and R. Now R is basically an inverted C, plus one vertical and one horizontal stroke.
Therefore
Ireland has three more than Iceland. (Yay! Shamrocks always win!)