First of all, if you sell to both retail consumers and to other businesses (at wholesale), you are truly running two separate businesses. You should be tracking sales and analyzing data for both of these businesses separately (to really optimize them individually). While analyzing the data separately is still possible on a combined wholesale/retail website - it's definitely more challenging (and perhaps not the best use of your precious time).
Ok but say we forget about how a combined site makes things harder for you in the bigger picture. Think about your customers too! Your retail and wholesale customers have completely different needs and desires - in a combined site someones needs and desires are not going to be spoken to as well as the other. Meaning your site will need to be made to somehow cater to both (which actually means you will end up mostly catering to one or the other, usually whichever leg of your business is doing best). If you have two totally separate websites, you can 110% cater specifically to the audience at hand (think website layout, menu, email flows, the wholesale application process, upsell offerings at checkout, the email subscriber pop-up box, all the little details can now be exactly meant for your specific website visitor).
Again, these are all easier (and lower cost monthly) when you have totally separate websites for retail vs. wholesale. However, with the right apps this is all still possible on a combined website as well.
Again, the app/s you will use here will depend on whether your website will be catering to wholesale only or both wholesale/retail. But either way, you will want a way to hide/lock wholesale pricing to anyone who you have not already approved! Locksmith is our go-to app recommendation to assist with this (though sometimes you will need a fancier app, particularly if you have a combined wholesale/retail website).