Chiffchaff or Willow warbler?

Chiffchaff or Willow warbler?

Observation - Chiffchaff or Willow warbler?. Description: I know that the first chiffchaff's have arrived back into the area as I have heard them, the one in the picture didn't make any noises (calls) so I am unsure. any suggestions would be greatly appreciated. it was feeding very briefly hopping almost through

I know that the first chiffchaff's have arrived back into the area as I have heard them, the one in the picture didn't make any noises (calls) so I am unsure. any suggestions would be greatly appreciated. it was feeding very briefly hopping almost throughout the tree, does what its feeding on give any clue to its identity?