closure-like constructs

# So in fact, there are no less than seven -- count 'em, SEVEN -- different closure-like constructs in Ruby:
#
#      1. block (implicitly passed, called with yield)
#      2. block (&b  =>  f(&b)  =>  yield)
#      3. block (&b  =>  b.call)
#      4. Proc.new
#      5. proc
#      6. lambda
#      7. method
#
# Though they all look different, some of these are secretly identical, as we'll see shortly.
#
# We already know that (1) and (2) are not really closures -- and they are, in fact, exactly the same thing.
# Numbers 3-7 all seem to be identical. Are they just different syntaxes for identical semantics?