what's the difference betweem a cc motorcyle and an R one

150cc refers to the engine capacity in cubic centimetres (area of the cylinder cross-section x stroke). 150R is a model number which may (and usually does) refer to the engine capacity. The 'R' could mean anything the manufacturer chooses it to mean. It may stand for 'Regular' or 'Road', for example and they may have other 150cc machines with the model number 150S or 150X (depending on the manufacturer). Different machines may use the same size engine but may have different gearing, different compression ratios and many other factors influencing performance, suitability for purpose, styling and so on.