Language evolves over time.
In his book Stages of Faith, James Fowler describes how the word "believe" has changed over the centuries - a change which has done great damage to the Church as a result.
In our earliest Bible translations, "believe" was the English word of choice to translate the Greek pistuo, as in "believe in the Lord Jesus and you will be saved".
Here's the problem: what we understand by the word "believe" today is a pale shadow of what the word once meant.
The earlier meaning was much closer to what the Bible has in mind when it speaks of belief and faith. Today's "believe" falls far short of the meaning carried by the Greek.
Once upon a time, "believe" meant "to hold dear, to love, to consider valuable or lovely". "Belief" was something you directed towards a person, not an idea.
Fowler quotes Wilfred Cantwell Smith on the difference:
"There was a time when 'I believe' as a ceremonial declaration of faith meant, and was heard as meaning: 'Given the reality of God, as a fact of the universe, I hereby proclaim that I align my life accordingly, pledging love and loyalty.' A statement about a person's believing has now come to mean, rather, something of this sort: 'Given the uncertainty of God, as a fact of modern life, so-and-so reports that the idea of God is part of the furniture of his mind.'"
And so the modern "believer" is often proclaiming nothing more in their "belief" than that, in Fowler's words, they give "assent to a set of propositions" or commit "to a belief system".
That is not the same.
At all.