Resonator ukuleles have special metallic cones that resonate and amplify the sound produced by their strings. This is unlike a typical uke which resonates sound primarily through its top wood. As far as ukuleles go, resonators couldn't sound more different to standard four-strings. Bright, triumphant, with incredible projection. In fact, the best resos are much louder than any uke we have in stock.
Thankfully, the tuning is the same. So all the chord shapes you have committed to memory won't go out the window. The only minor difference is that sometimes the high G is strung low, which compliments the depth and bassy undertones of the instrument.
In the 1920s, resonator guitars were produced to compete with the much louder accompanying instruments in orchestras. They became a hallmark of bluegrass music which emerged soon after in country America. Since then, ukuleles have adopted a similar approach. Ukuleles with semblance to resonator guitars have popped up across the world, experimenting with different shapes, sound hole arrangements, body material varieties, and cone types. The history of resonators is rich and ever-growing.