How to plot similarity of two datasets?
Here is an example of r lattice xyplot using log scale on the x axis and the difference of your two measures I(expected - simulated)

df &lt;- data.frame(
x         = c(2, 4, 8, 16, 32, 64),
expected  = c(47.9995, 95.9783, 
191.9127, 383.9708, 767.8831, 
1457.2771),
simulated = c(48, 96, 191.8, 383.8, 
767.4, 1458.1228))
xy &lt;- xyplot(I(expected - simulated) ~ x ,   
auto.key=TRUE,
data =  df ,    type=c("p","g"),
scales=list(x=list(log = 10) ),   
ylab="difference expected - simulated", xlab="x", main="Simulation Results" )
print (xy)


Note, that I added a 6th result to your sample data,that was missing.