Here is a PATRIARCH who practiced both Theravada and Mahayana in Vietnam. One thing except all of his monks were vegetarian strictly. They walked for food, yes. Vietnamese people know to give monks vegetarian food. http://www.youtube.com/watch?v=ZPFS46qF5Yo
As for Arhat, Boddhisavatta, and Buddha. These are just potentials that all sentient beings can be. What destination is yours?
If I may ask this question that has asked by many: Where is your mind (citta)? Mind here does not mean the 6th consciousness but means Buddha Nature. Even if you disagree, please answer my question. Buddha Nature from my understanding contain all and nothing is outside of it. You can say 'it' is infinite.
Does Dependent Origination not speak of 'ignorance' Buddha Nature that has created everything that is in existence today? Imagine what a Buddha can do.
Buddha not = Arhat for Sakyamuni Buddha had disciples who were enlightened or Arhats but they were not Buddhas.
By the way, Mahayana teachings do not stray away from Fourth Noble Truths and Dependent Origination or 12 Conditional Factors. You will have problems if you do not understand 12 Conditional Factors and if your knowledge is solely based on history and subjective philosophies (from lack of understanding of basic teachings).
Fourth Noble Truths in Pure Land for example
1)There is Suffering
2)Cause of Suffering
3)Pure Land (a place in the mind) is the answer instead of Nirvana (a place and some say a state of mind but where is mind? ahhh)
4)Practice Pure Land with diligence
The difference here is still compassion which is an act to save other sentient beings also. This is the reason why Theravada people have a problem with Bodhisattva is that in Theravada's view: when a Arhat is realized, this enlightened being would dip out to Nirvana. Other enlightened beings who come back or vow to help other sentient beings by many means necessarily. These enlightened beings are Bodhisattvas and Buddhas who carry different potentials than those of an Arhat. But remember Buddha is the ultimate potential that every sentient being can be thus we all are equal in this sense, so choose your path. For example, Amitabha Buddha who vowed to help other sentient beings to be reborn in his Pure Land (where is Pure Land?ahhh). This is the reason why Theravada people seem to disagree with Amitabha and other Buddhas...an Arhat can make vows to become a Bodhisattva if this being wishes to.
I apologize if I sounded superior to Theravada people for this is not my intention but I am still a human being. By the way some Mahayana people it is easy to realize Arhat...NOT...in fact rarely any these days lol and even Zen Meditation, tantra, or whatever rarely seen one. Call me crazy, typical, extreme, lunatic or fundamentalist for I care I am going on a boat of Amitabha. Why because I practice and I experience changes in my life...Ahem as for those who make Bodhisattva's vows, and you can't observe samadhi or samatha in this life time, you might have a big problem in the next life as you may not remember anything at all. So the good path right now is Amitabha as far as I can see it.
You can talk all your life but if you don't practice, then it is empty talk and can never experience the flavor or taste of Buddhism.
Lastly, Compassion...well compassion is to practice[any practices including meditation (not the sitting one but the detachment from everything/forms one sees in everyday's life), giving,etc] completely letting go of self in order to serve other sentient beings. Every thought and act is about other sentient beings. This practice of compassion is a practice in every aspect in everyday's life in interaction with sentient beings (e.g., people) and environment. Meditation as mentioned earlier is not about sitting in one place but about practicing detaching on the inside in every interaction with sentient beings and environment. In other words, practice not reacting with senses and consciousnesses to forms and calm inside. So this is is basically practicing Bodhishavattahood or path.
Don't beat me up for this lol.