Test the difference between two different lists

I've a two lists. One is (Pred) is the output of an algorithm. The other one, (Obs), are the real observations the algorithm should provide.

    Pred    Obs
    Head-up Vigilance
    Head-up Vigilance
    Head-up Vigilance
    Head-up Vigilance
    Head-up Vigilance
    Head-up Vigilance
    Head-up Vigilance
    Head-up Vigilance

I would like to test how different both lists are. Both columns have the same number of rows. I'd normally use a Chi-Square test if these were values (Expected/Observed), but here I have words instead.

Any ideas? I'm trying to test how accurate my algorithm is to predict real observations. I'm coding with R.

Any input is appreciated!