difference between actual code and codelab code

[minchanpark]

// TODO: Add TextField widgets (101)
// [Name]
TextField(
decoration: const InputDecoration(
filled: true,
labelText: 'Username',
),
),
// spacer
const SizedBox(height: 120.0),
// [Password]
TextField(
decoration: const InputDecoration(
filled: true,
labelText: 'Password',
),
obscureText: true,
),

it is different between actual code and codelab code.
"const SizedBox(height: 120.0),"-->"const SizedBox(height: 12.0),"