The difference between a banjo and a banjolele is the tuning. Most ukes/banjoleles (not all, but most) use similar intervals to the intervals of the top 4 strings of a guitar - though in different keys. The 4th string is usually re-entrant, as for example, g-C-E-a

A tenor banjo is normally tuned in 5ths - either in viola tuning (CGDA) or in octave mandolin tuning - though, once again, there are variations - and a 5-string G banjo is usually tuned to a chord such as G.