Suit and Tuxes are two different styles of clothing… just like pants / trousers & jeans are two different things… you wear them for different occasions.
A Tux generally speaking has satin or grosgrain lapels, and sometimes a corresponding stripe down the outside pant leg. Tux trousers cannot accommodate a belt… one covers the waist band with either a Cummerbund or a Vest. If one needs assistance in keeping their pants up / in place, suspenders are worn.
A Tux is traditionally worn with a shirt with french cuffs (cuff links) and matching studs. The shirt will eithter have a wing collar or a flat collar… neckwear is chosen depending on the shirt collar… bowtie, ascot, windsor tie, and also depending on the formality of the occasion
A basic rental tends to run anywhere from $ 100 and up to several hundred dollars depending on where you live. Which is why for some people buying makes more sense.
One can often purchase a tux in the $ 200+ range… lowerend for “gently worn”… high for new and Designer Namebrand (ie Oscar de La Renta etc). New midrange can be found at some Department Stores (say $ 300 to $ 500 all in with everything required)
Buying a Tux is a good idea vs renting, if you see yourselves taking part in more formal occasions in the future. Example, Mr TTR owns a tux because we enjoy cruising, and attend several fundraising galas annually (but then again we are older than most newlyweds). My Ex Husband also owned a tux, but it was something he acquired in his 40s, for similar reasons.
A suit, is well just that, a suit of clothing (matching pieces). It could be a basic 2 piece (Jacket & Pants) or a 3 pc (plus vest) or 4 pc (extra pair of pants). Suits can be all over the map pricewise… a basic 2 pc can be found for even under $ 100. BUT when it comes to pricing a lot will depend on Quality. The better the fabric & construction the more it is going to cost (both suits & tuxes can go right on up into the $ 1000s of dollars)
IMO, every grown man should own a dark suit… Black, Charcoal or Midnight Navy. A Suit can be worn to a Job Interview, Wedding, Funeral, or many other more dressy formal occasions (even the most formal of situations one can usually get away with a Black Suit).
Hope this helps,