first_dict = {}
second_dict = {}

value = set(second_dict)-set(first_dict)
print value

value = { k : second_dict[k] for k in set(second_dict) - set(first_dict) }

test_1 = {"foo": "bar", "FOO": "BAR"}
test_2 = {"foo": "bar", "f00": "b@r"}

{"foo": "bar", ...}

set_1 = set(test_1.items())
set_2 = set(test_2.items())

print set_1 - set_2
>>> {('FOO', 'BAR')}

dict(set_1 - set_2)
>>> {'FOO': 'BAR'}

>>> dict1 = {1:'donkey', 2:'chicken', 3:'dog'}
>>> dict2 = {1:'donkey', 2:'chimpansee', 4:'chicken'}
>>> set1 = set(dict1.items())
>>> set2 = set(dict2.items())
>>> set1 ^ set2
{(2, 'chimpansee'), (4, 'chicken'), (2, 'chicken'), (3, 'dog')}

>>> set2 ^ set1
{(2, 'chimpansee'), (4, 'chicken'), (2, 'chicken'), (3, 'dog')}

>>> set1 - set2
{(2, 'chicken'), (3, 'dog')}
>>> set2 - set1
{(2, 'chimpansee'), (4, 'chicken')}

>>> dict(set1 ^ set2)
{2: 'chicken', 3: 'dog', 4: 'chicken'}

import dictdiffer

a_dict = {
  'a': 'foo',
  'b': 'bar',
  'd': 'barfoo'
}

b_dict = {
  'a': 'foo',
  'b': 'BAR',
  'c': 'foobar'
}

for diff in list(dictdiffer.diff(a_dict, b_dict)):
    print diff

('change', 'b', ('bar', 'BAR'))
('add', '', [('c', 'foobar')])
('remove', '', [('d', 'barfoo')])