This answer may apply to other countries but is pretty cert for the UK.
Bird feed sold in the UK (from big chain pet stores, to garden centres, to little corner shops) usually comes with a time of year printed on the packet. This can be Spring-Summer, Winter or All Year for example. Which is because we get a cycle of birds throught the year and what is good for one species isn't good / appetising for all.
A brilliant bird food list can be found on the RSPCB websites What Food to Provide page.
Good autumn / winter feeds are:
- Fat balls or bars
- Black sunflower seeds
- Cooked rice (when food is incredibly scarce)
- Any feed with large chunks of nut in, these are suitable for winter only.
Mealworms and black sunflower seeds are good all year round feeds, used to supplement a birds diet.
The type of seed does make a big difference to what is attracted to your garden.
Small seeds, such as millet, attract mostly house sparrows, dunnocks, finches, reed buntings and collared doves, while flaked maize is taken readily by blackbirds. Tits and greenfinches favour peanuts and sunflower seeds. Mixes that contain chunks or whole nuts are suitable for winter feeding only. Pinhead oatmeal is excellent for many birds. Wheat and barley grains are often included in seed mixtures, but they are really only suitable for pigeons, doves and pheasants, which feed on the ground and rapidly increase in numbers, frequently deterring the smaller species.
To attract in numbers you may need to provide a mix of feeds.