How can we compare human language and animal language?
Primarily by the degree of complexity as well as commonalities.
"Language" is really the medium of communication. What combination of auditory and visual signals are used can be infinite in variety - even amongst humans, much less diverse animal species!
So, the best initial "comparison" is about the complexity (here I include flexibility in expressing difference nuances of meaning) and commonalities - those things common in all languages across all species.
In general, the commonalities are the same - vocally produced sound patterns are related to specific concepts or ideas. They are understood purely as a auditory sense, although other visual cues may be added to enhance the communication.
The complexities are where human languages far exceed any known animal languages in terms of range of expression, nuances of meaning, and particularly the understanding of abstract concepts.