Difference Between Two VB.NET LINQ Group By Syntaxes

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VB

LINQ

I have been playing around with grouping items using LINQ, and I am not sure if there is a difference between these two syntaxes:

Dim categories1 =
    From p In products Group p By p.Category Into Group,
        TotalUnits = Sum(p.UnitsInStock), ProductCount = Count()
    Select Category, Average = TotalUnits / ProductCount

Dim categories2 =
    From p In products Group p By p.Category Into
        TotalUnits = Sum(p.UnitsInStock), ProductCount = Count()
    Select Category, Average = TotalUnits / ProductCount

In the first, I do "Into Group," and in the second I do "Into". It seems that the "Group" in that case is a keyword rather than the name of the group. Both syntaxes appear to produce the same result. Is there a reason these two syntaxes exist (e.g., can one be used when the other cannot)? Is the second syntax just shorthand for the first?

Here is a class and function you can use to test the above queries, if you like:

Public Class ProductClass
	Public Property Category As String
	Public Property UnitsInStock As Integer
End Class
Public Function GetProductList() As List(Of ProductClass)
	Return New List(Of ProductClass) From {
		New ProductClass With {.Category = "A", .UnitsInStock = 5},
		New ProductClass With {.Category = "A", .UnitsInStock = 3},
		New ProductClass With {.Category = "B", .UnitsInStock = 4}}
End Function