I'm not sure I see the difference. Can you explain further?
Spurgeon was using it in reference to the salvation of men. We come to God and plead the blood of Christ in our salvation. It is because of the blood of Christ that we are saved.
Pleading the blood, after salvation, as a means to get God to honor our prayer request as if it makes our request a sure thing as a result of doing so in not in fact biblical.