Clarify sync vs. async enumerable objects.

Author: BillWagner

standard/classes.md

@@ -5599,10 +5599,9 @@ The `Dispose` or `DisposeAsync` method is used to clean up the iteration by brin
 
 When a function member or local function returning an enumerable interface type or an async enumerable interface type is implemented using an iterator block, invoking the function does not immediately execute the code in the iterator block. Instead, an ***enumerable object*** is created and returned.
 
-The enumerable object’s `GetEnumerator` or `GetAsyncEnumerator` method returns an enumerator object that encapsulates the code specified in the iterator block, and execution of the code in the iterator block occurs when the enumerator object’s `MoveNext` or `MoveNextAsync` method is invoked. An enumerable object has the following characteristics:
+A synchronous enumerable object implements `IEnumerable` and `IEnumerable<T>` or `IAsyncEnumerable<T>`, where `T` is the yield type of the iterator. Its `GetEnumerator` returns an enumerator object (§15.15.5). An async enumerable object implements `IAsyncEnumerable<T>` where `T` is the yield type of the iterator. Its `GetAsyncEnumerator` returns an asynchronous enumerator object  (§15.15.5).
 
-- It implements `IEnumerable` and `IEnumerable<T>` or `IAsyncEnumerable<T>`, where `T` is the yield type of the iterator.
-- It is initialized with a copy of the argument values (if any) and instance value passed to the function.
+An enumerable object is initialized with a copy of the argument values (if any) and instance value passed to the function.
 
 An enumerable object is typically an instance of a compiler-generated enumerable class that encapsulates the code in the iterator block and implements the enumerable interfaces, but other methods of implementation are possible. If an enumerable class is generated by the compiler, that class will be nested, directly or indirectly, in the class containing the function, it will have private accessibility, and it will have a name reserved for compiler use ([§6.4.3](lexical-structure.md#643-identifiers)).