I'm guessing half because I have double that amount in hp.
Yeah bro, don't get entangled too much. You can currently have double, triple or ten times the HP indicated by both Hivetasks and Hivebuzz. But that's only because you may have purchased Hive in the market that you Powered Up or because you've rented it or had it delegated to you by someone else.
While what Hivetasks shows in the pictures I gave you and what Hivebuzz shows in its statistics, is exclusively the HP that you actually have earned from "curation rewards" through the upvotes you have given and the "author rewards" you have earned through the upvotes that others have given to your own content. Posts and comments. :)
We need an explanation as to why there is so much variation in the amounts.
There is no variation really. What Hivetasks and Hivebuzz indicate is only the HP you have earned during the entire time you have been in the chain, but exclusively coming from your content curation and content production. It doesn't matter how much HP you currently may have in your wallet that comes from other sources. That's all.