Things like Roger having the same hat, Rayleigh seeing Roger in Luffy when he said that he wanted to be the most free man, the voice of all things, pretty similar personality from what've seen, and a couple of other parallels are pretty annoying. Then again, most shounen have parallels with previous generations... and the new generations usually surpasses the previous one. Will definitely happen in OP too. What also will happen is that we're going to get more Luffy-Roger parallels, just so that Oda will be sure that we know how incredibly similar they are
I never liked drawing obvious parallels with the previous generation(s) in any manga
Both first mates are swordsmen, and they like alcohol if that helps understanding why people think they are a like. imo, they also aren't that different in personality.
edit: why are there like 7 posts comparing it to Naruto. The OP said nothing about Naruto
That description is so superficial that if that would be the standard, countless of characters would fit it.
Like alcohol? I'm pretty sure loving alcohol isn't a rarity among pirates.
Swordsmen? That's actually very relative as so far Rayleigh hasn't really shown being a 'swordsman', but just someone who uses a sword as a weapon. There's a very subtle difference between the two. Oda has made people like Zoro, Mihawk, Vista, Tashigi appear like real swordsmen who trained their whole life with swords with the point of being a swordsman, often having high-grade swords and have a special connection with their swordsmanship. Then you have got people who just use swords as weapons. Yes people like Shanks and Rayleigh are beyond all doubt extremely skillful with the sword, but they use just regular cutlasses (as far as we know), there isn't any meaning in their swords. They just use them as tools to fight like countless characters.
That alone sets Zoro, who is driven in becoming the best swordsman in the world, completely apart from Rayleigh who has never shown any special interest in swordsmanship other than a means of combat.
Rayleigh is a very intelligent man that can easily keep a low profile and is most of the time composed. That doesn't sound like Zoro at all. The only thing where Zoro and Rayleigh are similar is how they stand in comparison with Luffy and Roger. As Sanji said when people think of Roger's crew, the first person they think of is the Dark King Rayleigh. When people think of Luffy's crew, they think of Zoro. This probably why people subconsciously see Zoro as Luffy's Rayleigh, however as individual characters they are very different. At least based on how he is now as we don't know how he was in the early days with Roger.
Scar? Alcohol? Using a sword? Those are such shallow reasons that if they really are used to compare them, by default Zoro and Rayleigh are very different.
And the reason as why people make so much references to Naruto is because Kishi drew so much parallels between certain characters, any kind of parallel in OP seems like a joke or coincidence.