Yep OT is more function based and works on activities of daily living like washing, dressing, eating, cooking etc... they will help teach patients how to do things like transferring from a bed to a chair, into and out of a bath, on and off the toilet, how to get into bed after having a hip replacement etc. OT's will also work with people developing skills like memory, numerical skills, processing information and other brain-related tasks! Like Physio's, OT's rotate around different specialties like neurology and orthopaedics and may do different things based on which area they are in. I work as a physio and thats the sort of things our OT's do anyway!!
On the other hand Physio's mainly work with physical movement- regaining it or improving it following injury or illness, e.g. after a stroke, after a fracture, after falls etc. Specific techniques to do this would include improving muscle strength, improving balance, improving walking patterns etc...Respiratory physio's work with patients post surgery or with breathing difficulties like asthma, or patients in intensive care. Basically to improve their breathing and maintain good lung function after surgery etc. Physio's also rotate around different clinical areas and can work anywhere from patients homes to hospitals, to clinics, intensive care and many other places.
I hope you'll see that they are very different jobs but the roles do sometimes actually get a bit of overlap, for instance both OT's and Physio's would be involved in improving a patients ability to transfer from a wheelchair to a bed as it involves a activity of daily living (getting into bed) as well as a physical movement (having the strength in the arms, trunk and legs) to get across to the bed.
I hope that helps!! I would recommend shadowing both a physio and an OT to get an idea of which you'd prefer.