From what I've read, the Buddha is debated to be an actual person whose teachings were followed, though some folk regard him as a spirit. Hekate is regarded as a multi-cultural deity.
When it comes to spirits and deities, they are not physical beings like you and I; they are incorporeal, nonphysical, and (the term I like to use most) subtle (in this context, it is paired with Occult, meaning Hidden as both refer to aspects of existence that aren't as apparent). However, Hekate isn't seen as subtle in the sense of discreet. She's actually a deity most who have researched wouldn't recommend to the average practitioner.
Mihans, the concept of being a buddha is a bit varied among different beliefs, but a buddha is a person who has achieved enlightenment. It is the goal of most buddhists. Buddha is not one person, but a type of person. In fact, there is the belief that there are (will be) a certain number of buddhas throughout time, and the next (who some have claimed to be) should be soon in coming.
Buddha is not a statue. The statues represent different Buddhas and beliefs about those individuals, and what they accomplished. A person (it is believed) can achieve the state through many, many years of meditation, study, and dedication.
Hecate is a Greek Goddess (or Titaness, if you wish. Sources differ.) who is associated with magic, crossroads, travelling, the cycle of life, the underworld, and other things. She was often seen as a patron of the downtrodden, runaway slaves often prayed to her. Hecate is close friends with Persephone and Hades. Zeus made no attempt to take her power after defeating the other beings before him. I personally work with her and have found it to be very rewarding, but she is not for everyone. She was my first Patron Goddess ater I left Christianity, and I would recommend her to any who are curious and wise.