Neither term is more technical. There are certain contexts where there is a difference between the two words. COCA is a good resource for answering such questions in the future. Yes there are objective criteria.
Generally speaking loudspeaker and speaker (in the context of a stereo system) are synonyms. However... I've heard many aficionados use the term loudspeaker pejoratively to indicate the sound quality isn't good enough for their well trained earsthem.
The pejorative quality comes from the comparison to speakers used for public announcements. (ie a PA system) Speakers used in PA systems are loud, but otherwise not very good. A corpus search shows that loudspeaker almost always refers to sound systems used by activists, police, firefighters, stadium sports announcers, etc. They are used in public places both outdoors and indoors where loudness is more important that their dynamic range.