λόγον Θεοῦ (logos,) and ῥῆμα Θεοῦ (rhema)
The difference is well worth understanding, although it depends on your theology. Man is a spirit, posses a soul, and lives in a body. And, man can ‘hear/see’ with his physical ‘ears/eyes’, but, can also ‘hear/see’ with his spiritual ‘eyes/ears’. Your ‘soul’, that part of you that ‘acts/does’, that part that ‘moves’ or ‘motivates’ the body [will] can listen to, and act on either - that is, can be motivated by your spirit, or your body.
Jesus often exclaimed ‘you have ears, but cant hear, eyes, but can’t see’. This referenced what I briefly tried to explain. And, Paul exhorted believers to ‘live in the spirit’.
Now back to the question. Logos you hear with your ‘physical’ ears. So you naturally hear it, and the either reject/accept/contemplate/meditate and then possibly act on it.
We see that in Luke 5:1 (λόγον Θεοῦ)
LUKE 5:1 So it was, as the multitude pressed about Him to hear the word of God
If we look a little further down, in verse 5, we see ῥῆμα Θεοῦ
LUKE 5:5 But Simon answered and said to Him, “Master, we have toiled all night and caught nothing; nevertheless at Your word I will let down the net.”
Here we see Peter firstly reasoning out what he heard Jesus say, but then his spirit ‘perceived [saw]’ ‘something’, and then he acted on the word. Rhema is when your ‘inner man’ [spirit] causes you to ‘act’
Essentially, the word of God [Logos], in and of itself will have no ‘effect’, [or ‘life’] until your spirit ‘sees’ it. This is what revelation is/means. Revelation is when your spirit ‘sees’ or ‘hears’ the word. So , Rhema refers to spiritual hearing/seeing. And it is when that occurs that the ‘word’ has ‘life’.
Now this difference becomes clear in the Ephesians passage you list
EPH 6:17 And take the helmet of salvation, and the sword of the Spirit, which is the word of God;
And, consider the following ...
HEB 4:12 For the word of God is living and powerful, and sharper than any two-edged sword, piercing even to the division of soul and spirit,
It is important for believers to ‘listen’ to their spirit. That ‘word’ which their ‘spirit’ has ‘seen’ - what some refer to as ‘believe in your heart’ - which often conflicts with what your ‘natural’ eyes are seeing. The Ephesians passage is exhorting believers to rest in what their spirit [rhema] knows, that ‘word that is in your heart’, what you ‘believe’. What you ‘know’ [perceive in your heart/spirit]. When you hear/read Logos, there are times your [natural] reasoning will conflict with what your heart [rhema] is saying, as with Peter in that Luke incident, but rhema leads to life.
