On a technical level, fibre uses the transmission of light signals through glass fibre cables. Fibre is capable of much higher speeds than DSL (DSL services come in flavours of ADSL and VDSL with the latter being the latest version capable of speeds up to 40Mbps). Fibre can reach up to 1000Mbps, depending on the package you selected from the services available. Because fibre makes use of transmission at the speed of light, the signal between points is much faster than DSL and LTE. Therefore, fibre has a much-reduced latency leading to a better online experience. Reduced latency generally affects the speed of downloading emails and files, loading websites, streaming videos, etc.
DSL sends electrical signals along copper cables. DSL is affected by weather conditions. DSL is particularly affected by lightning strikes (and when copper thieves strike).
LTE sends wireless signals between cell phone towers on specific wireless frequencies. LTE is capable of similar speeds to fibre but at a much higher cost for data.