Popular American Designer Ralph Lauren has many different lines of clothing and the quality and style vary  from line to line. If you are not familiar with them, many of the names sound similar. I offer you a list (probably not exhaustive or complete) of some of the Ralph Lauren menswear labels.

Polo University Club. As far as I know, this is the least expensive line from Ralph Lauren. It is, or was, intended to be a Young Men's Line. Quality is about average, nothing spectacular.   Many eBay sellers will try to pass this off as "real" Polo, which it is not. (see below)
CHAPS. There was a  time when CHAPS was the bottom of the hierarchy, but  no more. CHAPS  clothing has been made by  GRIEFF, I believe, which is a respectable  manufacturer.  I think the shirts were made by Hathaway at one time.  CHAPS tends to be conservative, in the All American- Mid Market sense. You will see fewer stylistic risks, but the quality is certainly acceptable.
LAUREN by RALPH LAUREN items have been showing up more and more in discount venues and catalogues. I believe these items, mostly tailored clothing (suits and sportcoats) are made in China. The quality is good for the price, but my suspicion is that almost nobody pays full price.  I am not certain whether this line is between CHAPS and Polo University Club, or just ahead of CHAPS. My experience is that it is nicer than Polo U.C.  While I have seen it in PRL outlet stores, I do not see any of it on the Polo.com webpages.
RALPH LAUREN BLUE LABEL items show up sometime, usually with the name of a high end department store. This is not necessarily POLO, but the items are made of quality fabrics.  I have seen RL dress shirts and sportcoats. Construction seems to be above average
POLO JEANS COMPANY is an official POLO line, and can be seen on their webpage. This line is mostly sportswear.
POLO SPORT is another sportswear line, with emphasis on athletic wear, mostly for skiing and tennis.
POLO GOLF is  also a sportswear line, though  they may include blazers and sportcoats in Small-Medium-Large sizing.
BLUE LABEL POLO is the original  Ralph Lauren Polo tailored clothing. It has been made in many different places and the sizing and quality will vary somewhat.  This line is generally nicer than anything mentioned so far and may have highly original stylistic touches. Some Blue Label tailored clothing (suits and sportcoats)  is/are  made in Italy, probably by Corneliani.
RALPH LAUREN PURPLE LABEL. This is the premium line. Purple Label suits have a distinctive English  look and feel, and have been made in the past by Chester Barrie. I believe they have also been made by Saint Andrew(s), but I am not certain where they are currently made. Look for such details as button flies, adjustable tabs on trouser waists instead of belt loops, etc.
POLO  (or RL) BLACK LABEL. This is supposed to be the SUPER PREMIUM line.
DOUBLE RL/RRL. This is a western/nostalgia inspired line that includes dressy casual jackets, but probably no suits. These garments have a strong "retro" feel to them.
RUGBY. This is a new young person's line, sold only in RL Rugby stores. It is supposed to be Polo with a strong edge. Many of the items have the Rugby skull and bones logo on them.  As far as I know, there are no Rugby suits and the blazers in this line are pretty casual.

It is important to know that, in addition to the Polo flagship store in New York and the Rugby shops, Polo Ralph  Lauren also operates (or at least licenses) a number of outlet stores, many of them along US I-95. Demand for clothing at these outlets is so great that some items are made specifically to be sold there.  These items may or may not be of the same quality as the Ralph Lauren/Polo items sold in high-end clothing or department stores. In some cases, the question is not so much one of quality as of formailty.  A specialty store may stock, for instance, tartan trousers that are hemmed to fit the customer.  The outlets may sell prehemmed tartan trousers, which are necessarily designed to fit less precisely.  Some eBay sellers will identify outlet goods, which may be useful in your searches.  

Ralph Lauren's name also appears on a wide range of formalwear.  I believe the broad categories above hold true for the formalwear as well. Purple Label is better than most of the others. There may be some "cadet" lines designed and intended to encourage brand loyalty among those who can't yet afford the best.

The Great Ralph Lauren empire also includes footwear.   Polo or Ralph Lauren shoes are made all over the world. With some exceptions, the best gauge of quality will be the country of origin.  The best Polo shoes seem to come from England, the US, and Italy. Many more are made in China and other places.  Again, formality and quality tend to follow price.

The same rules that apply for the rest of the marketplace apply to Ralph Lauren goods. If you are accustomed to buying shirts in exact sleeve lengths, "average" sleeve lengths may be a sign of lesser  goods. If you are accustomed to buying shirts in sleeve and neck sizes, (or coats in chest sizes) small-mediium-large sizing may be less precise than you are used to.  If you are buying pajamas or socks, chances are, you are expecting small-medium-large in the first place.

I hope this little guide has been of some help.  As with anything, the combination of a little learning and a lot of  careful observation will  keep your confusion at a minimum. You may wish to see some of my other guides, such as Wentworth Splains Trouser Motifs and Wentworth  Tradd's Mostly Useless Guide to Fame.  And, as always, I would appreciate your voting "yes" on helpfulness.

Thanks and Many Good Lucks to you,

WT