I have been both a police officer (9 years) and PCSO (2 years). A PCSO can be identified by blue epaulettes on their shoulders, and typically their caps have a blue matching band. They have no powers of arrest other than a regular citizen's arrest which every person has.

In general, PCSOs do not carry PPE (personal protective equipment) but wear body armor/"stab vests". Some forces like the British Transport Police and a couple of Welsh forces have allowed their PCSOs to carry and use handcuffs for the purpose of detaining someone until a police officer arrives.

They have limited "powers" given to them. They generally issue PNDs (penalty notice for disorder) for things like drunk and disorderly behaviour and low level summary offences like s5 Public Order Act (behaviour which is harassing, alarming or distressing in public). They can issue cannabis warnings (as far as I remember) and also issue fixed-penalty notices for vehicles obstructing the highway.

PCSOs are more involved in community interaction, being a "link" between the police service and the community, going to council meetings, meeting neighbourhood watch groups and working as part of a safer neighbourhood team involved in high visibility policing.

In London, PCSOs either work in a safer neighbourhood team (SNT) or for TfL (transport for london) and concentrate on transport issues on buses, or dealing with cyclists and other road users. PCSOs cannot specialise and cannot be in charge of investigating a crime (an 'OIC') and cannot interview suspects.

Police officers on the other hand have full powers of arrest, carry PPE (taser, cuffs, CS/PAVA spray, baton), can drive response vehicles on blue lights (with training) and specialise in other areas after a 2 year probation phase like traffic, dog unit, firearms etc.