Standard weights and Olympic weights are both used to perform weight training exercises. The main difference between the two types of weights are their size--Olympic weights are generally large and have a larger hole for the weight to slide onto the bar.
The history of strength training began in the fifth century, B.C., with Milo of Crotona. The barbell became popular in the late 1800s, and competitive Olympic weightlifting began in Budapest, Hungary, in 1905. Charles Atlas further popularised strength training in the 1930s, and the use of weights has continued to grow ever since.
Standard weights generally come in sizes of 0.5, 1.25, 2.5, 5, 10, 15, 20, and 25 kg (1.1, 2.76, 5.5, 11, 22, 33.1, 44.1 and 55.1 pounds). The standard barbell is usually 1.83 m (6 feet) in length (in some cases the standard bar can by either 1.53 or 2.13 m [5 or 7 feet] long). A standard weight barbell weighs in at 6.8 kg (15 pounds). The diameter of the hole in the middle of a standard weight, as well as the diameter of standard bars, is just under 2.5 cm (1 inch), much less than an Olympic bar. Standard weights are generally less expensive than Olympic and come in lighter weight sets when purchased as a set.
Olympic weights generally come in increments of 1.1, 2.2, 4.5, 11.4, 15.9, and 20.4 kg (2.5, 5, 10, 25, 35 and 45 pounds). The standard Olympic barbell is 5 cm (2 inches) in diameter, almost double the size of a standard barbell. The Olympic barbell is always 2.13 m (7 feet) long and weighs 20 kg (44 pounds), which makes it better equipped to handle heavier weights. Olympic weight sets usually start at 136 kg (300 pounds).
Standard weights are better suited for beginner and intermediate weightlifters. A standard weight set that includes a barbell and dumbbells allows you to do a variety of exercises that target all the major muscle groups -- your calves, quadriceps, hamstring, back, core, shoulders, chest and arms. Olympic weight sets are used by those who are serious athletes that are training for a sport or looking to add mass and strength. Olympic weights allow you to lift much heavier volumes, thus promoting muscle growth and strength.
It's important to consult a physician before starting any weightlifting regimen. Consulting a professional personal trainer is a sound idea because he or she will show you proper form, which will help you prevent injuries when lifting weights. Training with weights offers many health benefits. According to the Mayo Clinic, strength training can help you develop stronger bones, control weight, reduce injury risk, boost stamina, sleep better and control chronic conditions like back pain, diabetes and obesity.