Is there a difference between these 2 pieces of code?

General Usage
1 
struct MM
           abstract type TT end
           export TT
           MM() = new()
       end

vs

           abstract type TT end
           export TT
           struct MM end

Thanks?

2

Why would you write the first code? You can see what code is lowered to using Meta.@lower, @code_lowered

3 
:($(Expr(:thunk, CodeInfo(
    @ REPL[28]:2 within `top-level scope'
1 ─       global MM
│         const MM
│         $(Expr(:struct_type, :MM, :(Core.svec()), :(Core.svec()), :(Core.Any), :(Core.svec()), false, 0))
│         global MM
│         global TT
│         const TT
│         $(Expr(:abstract_type, :TT, :(Core.svec()), :(Core.Any)))
│         export TT
│         $(Expr(:method, :MM))
│   %10 = Core.Typeof(MM)
│   %11 = Core.svec(%10)
│   %12 = Core.svec()
│   %13 = Core.svec(%11, %12)
│         $(Expr(:method, :MM, :(%13), CodeInfo(quote
    %new(MM)
    return %1
end)))
└──       return
))))

vs

:($(Expr(:thunk, CodeInfo(
    @ REPL[29]:2 within `top-level scope'
1 ─       global TT
│         const TT
│         $(Expr(:abstract_type, :TT, :(Core.svec()), :(Core.Any)))
│   @ REPL[29]:3 within `top-level scope'
│         export TT
│   @ REPL[29]:4 within `top-level scope'
│         global MM
│         const MM
│         $(Expr(:struct_type, :MM, :(Core.svec()), :(Core.svec()), :(Core.Any), :(Core.svec()), false, 0))
│         global MM
│         $(Expr(:method, :MM))
│   %10 = Core.Typeof(MM)
│   %11 = Core.svec(%10)
│   %12 = Core.svec()
│   %13 = Core.svec(%11, %12)
│         $(Expr(:method, :MM, :(%13), CodeInfo(quote
    %new(MM)
    return %1
end)))
└──       return
))))