Channel 4 unfortunately doesn't have the breadth of news coverage (though they definitely have the depth) that the BBC has. They don't have anything like the local/regional news coverage and have to be very selective about what they report on. They're also 1 medium only (TV) whereas the BBC are TV, radio, and what is effectively the UK's biggest online newspaper.

They're also living on borrowed time. Channel 4 is publicly owned but completely self funded, largely through ad revenue. Ad revenue for TV is not what it used to be.

There's been serious consideration given to the idea of merging Channel 4 into the BBC to share admin costs but keep it editorially separate.