Acoustic amps are designed to produce cleaner, wider bandwith and a more natural sound. A passive piezoelectric pickup works better if an outboard device, like an LR Baggs Paracoustic DI is used before plugging in. The speakers on an acoustic amp are structured more like those in a home entertainment system. They usually have foam surrounds and stiff cones. Acoustic amps generally have a tweeter, coaxial tweeter or a whizzer cone to expand the bandwidth of the frequency response. This accommodates a more natural movement of the cone.
Electric guitar amps are built to amplify the frequency range and overtones of magnetic pickup/active electronics in a narrower frequency bandwidth for more efficency and acoustical output. The speakers, from companies like Eminence and Celestion, have more slop in the cones. The cone and the surround are one piece and of the same material. The surround is usually coated with a rubbery substance for more strength to prevent tearing at the cone edges.
Acoustic amps are generally closed back. This creates a flatter response as the output is quasicomplementary - push push.
Electric guitar amps are generally open backed. This boosts the acoustical midrange, as the acoustical output is a slightly out of phase - push pull - push comes out of the front of the amp and pull comes out of the back of the amp. This phasing delta cancels some of the bass and treble.
Electric guitar amps are designed for mor midrange. Play your uke through an electric guitar amp and then through an acoustic guitar amp. It sounds more natural through an acoustic guitar amp.
I can explain input biasing, if anyone is interested. Ric