Full fibre ‘FTTP’ doesn’t come from a cabinet , with other broadband technologies, if you get slower speed to your over the road neighbour ( assuming you are on the same product ) then it’s likely that the cable route they have is shorter to the cabinet/exchange than yours , assuming they are in the same cabinet/exchange area in the first place.
TBH , unless you are talking about an immediate neighbour, or you can see it’s the same telegraph pole that serves both ( underground feeds you obviously won’t know ) then it’s a pointless comparison, what have you done to establish your speed is as good as it could be ?
As already stated , what speed is predicted for your address , if it’s in line with that prediction that may all your location will provide, if it’s significantly less than the predicted speed you may have a fault, and that could be something you are responsible for ( rubbish internal wiring for example ) or Openreach are responsible for ( if it’s external to your home )
Post the connection statistics from your router , this may give an indication of an issue.
