at first glance

ad hoc ad lib automatic by ear casual expedient extempore free immediate impromptu improv improvisatory improviso informal jamming made-up makeshift off the cuff off the top of head offhand on impulse on-the-spot snap spontaneous spur-of-the-moment taking for ride thought out loud tossed off tossed out unplanned unpremeditated unprepared unstudied winging it

planned prepared read rehearsed written

outwardly

apparently carelessly casually externally extraneously flimsily frivolously hastily ignorantly not profoundly not thoroughly on the surface once over lightly ostensibly partially skim to the casual eye

carefully deeply thoroughly