As I understand it, EE use Band 3 and Band 7, while Three use Band 3 and Band 20.
It depends on area. They both have more bands than this. EE and Three both primarily use Band 3, but EE has more holdings in this band.
All 4 networks have Band 20, but EE and Three have 5mhz each, whereas Vodafone and O2 have 10mhz each.
All 4 networks have Band 3, but EE has 45mhz, Three has 15mhz, and Vodafone and O2 have 5mhz each.
All 4 networks have Band 1 (2100mhz) being switched from 3G (UMTS) to 4G (LTE) services
2 networks have Band 7 (2600mhz) - EE and Vodafone
2 networks have Band 32 (1400mhz) - Three and Vodafone - but this is downlink only.
Then the whole thiing gets a LOT more complicated when you add in 5G
You can see why some devices (notably the "gigabit" capable ones) have 5 way Carrier Aggregation, useful on both Vodafone and EE in many cities for additional capacity.
plusnet 80/20 (2/jun/14) at 470m - Sync history highest: 64/9 (Sep/17), 54/6 (Jan/19), 51/6 (Mar/19)
20 years of broadband from 1999's ntl:cable modem trial - Live BQM