Learn Spanish (Latin America): El ladrón habría atado la soga al árbol. - The thief would have tied the rope to the tree.

It can mean that in a different context, but here it expresses past conjecture. In Spanish, the conditional perfect is often used to make an educated guess about a completed past event. A more natural translation for this specific meaning might be 'The thief must have tied the rope to the tree.'

Could I use the future perfect (habrá atado) here instead to say 'must have tied'?

Yes, but the timeframe shifts slightly. The future perfect (habrá atado) is usually used to guess about the recent past or an action connected to the present. The conditional perfect (habría atado) is used when guessing about events situated further back in the past, often when telling a past-tense story or investigating an old scene.

Is there a difference between using soga and cuerda for the word rope?

Yes, though they are often interchangeable. A soga is typically a thick, heavy rope, often made of natural fibers like hemp. A cuerda is a much more general word that can mean anything from a thin string or a guitar cord to a regular rope.

Why do we use the preposition a in al árbol instead of en (in/on)?