The sentence structures are very common and both appear in the passive voice. I’m also sure Phil’s advice on studying the perfect infinitive is the way of understanding the way both sentences are written. Notice in both sentences „it’s believed“ and „the company is believed“ fails to identify who believes this. That’s passive voice, and it’s written this way either because the writer doesn’t know exactly who believes this or chooses to leave the actor(s) unidentified for some reason. So, keep that in mind and study the perfect infinitive as Phil suggested and I’m sure you’ll gain a better understanding of the structure of the sentences. However, they both indeed carry the same meaning.

Sezme has given you an excellent answer. For more information, Patryk, the search term would be “perfect infinitive”.

Hey Patryk! “Have lost” in this sentence is referring to a time in the past which was prior to the belief, which is now also in the past. We can use both forms that you have given us in American English. Please feel free to book a trial class with me so we can go over this in further detail. Hope this helps!