Have you watched my Dharma talk about the poem by Honen Shonin? If not, please watch it (It takes 9.31 minutes.....If you have time.) That youtube video is very important for me and maybe for both Jodoshu and Jodo Shin (Hongwanji) followers, because I got the difference clearly between Jodoshu and Jodo Shin after talking about the moonlight as follows;
Moonlight illuminates the world, leaving no corner in shadows,
But only those who gaze upon the moon, can appreciate its serene light.
Now, what, do you think, make you gaze upon the moon? I think Jodo Shin (Hongwanji) Buddhism regards moonlight itself as Amida Buddha's light. Moonlight is strong enough that you don't need any attention or effort or practice to look at. You can naturally look at the moonlight. So is Amida Buddha's light. The fact you noticed the light is actually a result that you already received the Buddha's light. This means you don't need practice to say Namu Amida Butsu. The fact to recite Namu Amida Butsu is a result that you received Buddha's blessing.
On the other hand, Jodo shu regards the action of gazing upon the moon as attention or making efforts or practice. By making attention toward the moon, we can receive the light. And by realizing the light of Amida Buddha, we can be attentive to receive Amida Buddha's original vow. When it's full moon, moonlight is so strong that we tend to think we can view the moon without any attention or efforts, but according to the teaching of Jodoshu, we need an attention or efforts or practice, no matter how small it may be.
So generally, "Namu Amida Butsu" for Jodoshu is a practice and "Namu Amida Butsu" for Jodo Shin is an expression of appreciation that you received the Buddha's vow. These are recognized as "absolute other-power(Zettai Tariki)" vs. "other-power (Tariki)."
However, what I realized was "Namu (or Namo) Amida Butsu" is "Namu (or Namo) Amida Butsu." We share the same action. The action to gaze moon is exactly same. What is the different is just naming of the action to gaze upon the moon, so-called explanations. The answers of the question, "What make you look at the moon?" are nothing. The action to look at moon, that is to recite nembutsu, is everything for both Jodo and Jodo Shin Buddhism.
Then what is the difference?
The biggest difference is, according to the Jodoshu, the more you gaze upon the moon, the more you can be good at viewing the moon. So is the Nembutsu. The more you recite nembutsu, the more you can be good at receiving Amida Buddha's light. Whether you call it practice or not, is not an issue but the fact you recite nembutsu is everything. And if you recite and recite and recite Namu Amida Butsu, and I think, one might reach Shinran's realization that stated no practice was necessary. I believe the fact Shin Buddhism was born from Jodoshu was very natural because Shinran Shonin devotedly followed his master, Honen Shonin. He must have recited Namu Amida Butsu many many many times as Honen taught and then Shin Buddhism was born.
So I have a feeling that teaching of Shin Buddhism is one of the results of following teaching of Jodoshu. Because that is result, their teaching is complete ; no room for practice of improvement is necessary. On the other hand, teaching of Jodo shu is nothing but reciting Namu Amida Butsu. There will be always something you get, as you recite more of Nembutsu.
I was able to realize this difference because I often photograph the moon. Usually, not many people don't notice the moonlight when it's croissant moon or day time. But because I often view the sky, I am now very good at finding the moonlight, day or night. And even if no more moon can be seen because of the cloud, then I can imagine its moon because of my attention to view the moon. I thought Namu Amida Butsu was the same. The more you recite "Namu Amida Butsu" and you will be good at receiving the light of Amida Buddha.