PCA plotting - What is the difference between ggfortify and ggplot?

Question

I'm new to PCA. I'm plotting the scores using autoplot from ggfortify and ggplot. Both have the same shape but have different values for the x and y axes. Eg. autoplot goes from -0.2 to 0.2 in the y-axis, and ggplot goes from -0.6 to -0.6. The points on the graphs look the exact same. Only the values of the axes changed. Why is that?

Edit: I can't really give the full data here as it's very long. I tried these two:

library(ggfortify)
pca.data <- prcomp(my_data)
autoplot(pca.data)

and

my_dataframe <- data.frame(Sample = rownames(pca.data$x),
                                       X = pca.data$x[,1],
                                       Y = pca.data$x[,2])
ggplot(data = my_dataframe, aes(x=X, y=Y, label=Sample)) +
  geom_point() +
  xlab("PC1") +
  ylab("PC2") +
  ggtitle("PCA Graph")

Answer 1

According to the vignette, autoplot scales in the same way as the biplot() function. If you don't want it to, you can instead use:

autoplot(pca.data, scale=0)

which (except for axis labels) gives the same at the ggplot command that you used.