All standardized Ballroom dances have various skill levels defined (Bronze, Silver, Gold, etc.). Basically, as the level of the dance increases, the patterns become more complicated and intricate but the fundamental movement stays the same. This is not true for American Style Foxtrot and Waltz. From a social dancing standpoint, I don't talk about the levels of the Ballroom dances except for Foxtrot and Waltz because the fundamental movement of these two dances is so very different at the Silver and above levels.
All of the "Rhythm" dances (Rumba, Cha Cha, Samba, etc.) utilize the same American Style Latin/Cuban motion at all levels of the dances. As the levels increase, the patterns become more complicated and intricate in both movement and rhythm (regular timing and various syncopations). From a social dancing viewpoint, it is not important to differentiate between the levels of the "Rhythm" dances because the fundamentals of the dances remain the same.
Not all of the "Smooth" dances; (Foxtrot, Waltz, Tango, etc.) adhere to this philosophy. Foxtrot and Waltz are the two exceptions. The Bronze (beginning) level of these two dances is quite different from the "Silver" and above levels. Simply stated, the dancer's feet/legs close to each other at the Bronze level and they pass each other in the Silver and beyond levels. This is a very important distinction for the social dancer. From a social dancing standpoint, I specify "Silver" Foxtrot and Waltz when I talk about these levels because they are almost different dances from the Bronze levels. Since these dances are fundamentally the same from Silver and up, I don't talk about any other level except Silver. The Bronze to Silver level is where the greatest differences exist in American Style Foxtrot and Waltz.
A couple of major differences between Bronze and Silver are the timing in Foxtrot and the rise in Waltz. The basic timing for Bronze Foxtrot is: Slow, Slow, Quick, Quick, (six counts) and the basic box timing is: Slow, Quick, Quick (four counts). The basic timing for Silver Foxtrot is Slow, Quick, Quick (four counts) only. The basic timing for Silver Waltz is the same as Bronze Waltz (1, 2, 3) but the rise is different. Bronze Waltz rises between the counts of one and two. Silver Waltz has something called "delayed rise". The rise happens at the end of count two. "Rise and Fall" is more important in Silver Waltz because of the leg swing that accommodates the passing of the feet/legs.
As stated in an earlier paragraph, the passing of the feet/legs is the primary difference in the movement between Bronze Foxtrot and Waltz and Silver Foxtrot and Waltz. The "shape" of the partnership is the element that allows the feet/legs to pass or not pass. If the leader dances a 90 degree box step, the dancers will close their feet/legs because as the side step is taken, the other foot/leg will be in the way and the feet/legs will close side-by-side. If the leader dances a box with shape, the feet/legs will cross either in front or in back depending on the shape created. This also results in the box having 120 degree corners.
"Left Side Lead" is taught at all levels of Smooth dancing but it is more important in the Silver and above levels because of the passing of the feet/legs. Each dancer in the partnership has their left side slightly forward. As the partnership moves, the partnership is moving slightly diagonal. The partnership now has a new direction for the forward and backward direction. Forward and backward is in relation to the direction if movement, not the shape of the shoulders of the dancers in the partnership. The left side lead accommodates the passing of the feet/legs and allows for "Outside Partner" dance position, which is critical to Silver movement.
CBM - "Contra Body Movement" is another key element for Silver movement. The definition of CBM is: turning the right side of the body towards a left moving leg or turning the left side of the body towards a right moving leg. The body and the leg must move at the same time, and not one after the other. CBM occurs on forward or backward steps only (or diagonal steps which still feature forward or backward movement), and not on side steps". The verbal description is rather hard to follow, but in general CBM again accommodates feet/legs passing.
I always try to teach students Silver Waltz before I teach them Silver Foxtrot. The Silver elements are transferable between the dances so it makes an easier transition if you are already familiar with Silver Waltz. It is generally accepted that the Silver and above Foxtrot is one of the hardest dances to master. The Slow step and the constant, level, smooth, even, movement makes Silver Foxtrot a challenge to dance at a high level.
As you can see from the above, there are a lot of required elements to be able to successfully dance American Style Foxtrot and Waltz at the Silver and above levels. It is a very difficult endeavor unless you take private lessons. There are a lot of complicated elements and partnership considerations. Silver and above Foxtrot and Waltz has an incredible feeling. It is very worthwhile and satisfying to learn. Just take your time and enjoy the learning process.