The theology is different.
You said Jesus put emphasis on faith (Buddha on action) but he put also emphasis on action. A tree is known by it's fruit...
Jesus puts emphasis on faith-faith saves not works. The general christian consensus is that works/actions can't get one to heaven and when ne goes to heaven they aren't reborn into another lifespan.
The Buddha puts emphasis on action. Right action keeps us from rebirth-that's the overall point.
Now let's see some other common points (correct me if I'm wrong).
1. Human need for salvation. Central in both Christianity and Buddhism is human condition - misery, entrapment in this world, spiritual blindness ... The cause is egoism - in Bible presented as alienation, in Buddhism identification with ego. Suffering comes from a fateful division in man.
Buddhism doesn't have an idea of salvation-in other words, no one is saving anyone on that person's behalf in the Dharma.
The human condition in christianity is of the soul and heart with most determining the problem with original sin.
The Dharma poses the problem of the mind. The attachments (gods for example of the Hindu tradition) and so forth are keeping the person "stuck" in this life from lifespan to lifespan. Relieving the ego is one way to do it. The theology in doing so differs in both traditions.
Also, the definition of ego is different.
In the Dharma, non-attachment to ego leads to cultivation for self in present state
The bible focuses on non-attachment to ego (though not expressed like that) one day in a future state.
In Buddhism, suffering is of the mind.
In Christianity, suffering is of the heart/soul.
2. Role of Christ and Buddha (The Anointed and The Awaken). Both have been over the years to some extent mythologized and turned into a simbol. Both represent a perfect/fulfilled/undivised man (or Man). Buddha doesn't live anymore from his ego but from deeper Reality (nirvana). Christ is a perfect union between man and God. He doesn't live for (and from) himself. He doesn't just talk about God's Kingdom but it is present in him.
In the Dharma awaken or enlightenment means end of rebirth and the current state is lack of attachment-from anything, gods included.
There is no concept of god in Buddhism like there is in christianity.
There is no union with anything in the Dharma as there is in christianity.
Everything is done by one's self in the Dharma.
Christianity needs god and christ.
3. Way of realizing Christhood/Budahood - transcending ego. Following Jesus is dying to self to give (spiritual) birth to Christ in me. In Christianity this is said to happen by the power of divine grace. Buddhist eightfold path on the other hand seems as self effort (independent of God). But also here enlightment cannot be forced. With eightfold path you only create good conditions. Awakening happens, spontaneously, as a gift (effort would be still in bounds of ego).
There is no "spirit-ual" in the Dharma as described in christianity
There is no divine grace or any divinity in buddhism as defined in christianity
the eightfold path leads to good actions (karma). Those actions leads to good conditions but just not attachment to them.
God and nirvana
Nirvana is the ultimate/transcendent reality. As I understand it's the same concept as mystery of God in apophatic theology. The difference is that Christianity also believes in God's revelation in history (divine face).
Heaven and nivanna are two separate concepts.
Heaven is an endstate and nivanna is a present state
God is a being, essence, a noun that one unites when "after" death.
Nivanna is the awaken state/mind (not soul) in that attachments are all gone and there is no rebirth. Nivanna is a present state of mental cultivation not a divine state where one joins with another.