I would say that the difference is very small, but that tiny difference is still a difference, and it also doesn't mean that it's very easy to overcome.
Some of misunderstandings that I've had on my way from 5 to legends were:
"It's all about the deck" - where in fact it isn't. You can make almost any deck to legend these days, it's all about how you pilot it
"Gotta counter the meta" - oh boy I was so wrong. It is impossible to counter meta, at all. The moment you switch from deck X to deck Y in order to counter decs A B and C, you'll start facing completely different decks. I also did and still do suspect ladder to be rigged in some way. Solution: just play decks that perform decently against the "global meta", don't even bother to counter your local meta, most of the time it's the wasting of time.
"But I'm doing nothing wrong, why am I still not in legend" - at some point it may seem like you're doing little to no mistakes. And it can actually be true. In fact, in my case, it turned out that I didn't know how to play 2 matchups with my decks. Yeah that's it, misunderstanding 2 matchups in the entire meta costed me those precious 5-9% winrate and instead of progressing I was just standing at the same ranks with around 50% winrate. Track your stats and find out your overall and matchup specific winrate, and try to compare your matchup winrates to what other people have with your deck (or what they say in "meta snapshots"/"power rankings").
"Losing streak again. Oh damn I'm rank X again" - both don't matter. Rank is just a number, so forget about it entirely until you're not in legend. Only care about your winrate. And if you're legend "first timer", I'd also suggest you to care about your last-3-days winrate, rather than daily winrate. Having streaks of bad variety is fine. If you're doing right moves in every game that may increase your winrate in the matchup, and you still lose it, then over time the rng will balance things out and you will eventually have positive winrate, that's how statistics works. Focus on your plays instead of bad rng.
So to me, the most important part was to work on my matchups. I used to have like 60% winrate with several decks in ranks 1-5, except for those 1-2 matchups, that were turning these 60% into 50-52%. And when you find it out, it's quite easy to fix your winrate in those matchups - just watch streams/videos or read a guide on what you should do in that matchup.