Yes, there is a difference. These two verbs do not have the same meaning.
'Have you observed any changes?' = 'Have you noticed any changes?'
'Observe' means to see, often as a result of careful watching - bemerken in German.
'Recognise' has a different meaning. When you recognise someone or something, you realise that you have seen them before - erkennen in German.
For example: 'Even though I hadn't seen Joan for 20 years, I recognised her immediately'.
It wouldn't be normal to say "Have you recognised any changes lately?". If a native English speaker said this, I would be a little confused. If a non-native speaker said this, I would presume that they were making a mistake and using the wrong word. The correct verb here is 'observed' or 'noticed'.