tuple versus Tuple

Question

Why do I get the following different results when converting a vector using either tuple or Tuple?

julia> a = [1, 2, 3]
3-element Vector{Int64}:
1
2
3

julia> tuple(a)
([1, 2, 3],)

julia> Tuple(a)
(1, 2, 3)

Broadcasting gives the same result though:

julia> tuple.(a)
3-element Vector{Tuple{Int64}}:
(1,)
(2,)
(3,)

julia> Tuple.(a)
3-element Vector{Tuple{Int64}}:
(1,)
(2,)
(3,)

(The latter is not so surprising as it just converts single numbers to tuples.)

(This is Julia 1.6.1.)