Difference betweeen DistilBertTokenizerFast and DistilBertTokenizer?

Hi everyone,

I’m trying to understand what is the difference between the DistilBertTokenizerFast and the DistilBertTokenizer.

From the documentation it looks like that the DistilBertTokenizerFast “Construct a “fast” DistilBERT tokenizer (backed by HuggingFace’s tokenizers library).” whereas the DistilBertTokenizer “Construct a DistilBERT tokenizer.”, but I don’t understand what that means.

This is what I found from the documentation: Tokenizer — transformers 4.5.0.dev0 documentation
To the best of my understanding the difference between a “fast” and a “non-fast” tokenizer is computation speed but there is no functional difference between them. Please correct me if I’m not the right direction.

Any help will be greatly appreciated.

Thank you,