Temple

https://www.templepurohit.com/difference-valmiki-ramayana-tulsidas-ramcharitmanas/

Rekha

The Lakshmana Rekha is not depicted in Valmiki’s Ramayana. Valmiki does not mention the existence of any line known as a Lakshmana Rekha. The episode on Sita’s abduction is contained in the Aranya Kanda. In chapter 45 of the book, the scene of Lakshmana, moving away from the hut, after folding his hands before Sita. He couldn’t bear her harsh criticism regarding not going to support Rama, who went out alone in the forest to fetch the golden deer for Sita. Lakshmana was reluctant to leave Sita alone, but he had to, when he saw Sita very tensed. The verses in chapter 45 and sarga 29 show that Lakshmana just moved away from Sita, with his hands folded. There was no verse depicting the presence of any kind of line. Tulsidas in Ramcharitmanas introduced the popular story of the Lakshmana Rekha, which was a perimeter drawn by Lakshmana around the hut, inside which any being or wild animal from outside would be destroyed. He drew this line to ensure Sita’s absolute protection within it. This story of the Lakshmana Rekha is really popular, and people still use it as a metaphor to signify situations where in a line should be crossed under no circumstances.

Kandas

Valmiki’s Ramayana is written in seven Kandas(books) known as Bala Kanda, Ayodhya Kanda, Aranya Kanda, Kishkindha Kanda, Sundara Kanda, Yuddha Kanda, and Uttara Kanda. Even Ramcharitmanas is divided into seven books, or Kandas.

However, Tulsidas renamed the Yuddha Kanda as the Lanka Kanda. This is one of the major differences between Ramayana and Ramcharitmanas.

General Differences

General Differences :-

1. Ramayan was written by Sage Valmiki who was a contemporary of Lord Ram. It was written in Sanskrit. Ramcharitmanas was written by Goswami Tulsidas in the 15th century C.E. It was written in Awadhi language.
2. Ramayan translates to Ram’s Journey whereas Ramcharitmanas means Bof Deeds of Lord Ram.
3. Ramayan has been written in ‘Slokas’(essentially a form of couplets) while Ramcharitmanas has been written in ‘Chaupais’(quatrain verse) .
4. Ramayan is the original version of Ram’s story (debated) while Ramcharitmanas is a retelling of the Ramayan. Tulsidas even acknowledges Valmiki in his book.
5. Both the books are divided into 7 parts known as ‘Kaands’. 6of the seven parts have the same name however, the penultimate kaand is known as ‘Yuddha Kaand’ in Ramayan and ‘Lanka Kaand’ in Ramcharitmanas.

Differences in Story :-

1. Dashratha has 3 wives according to Ramcharitmanas while he had 350 according to the Ramayan out of which 3 were principal wives.
2. Lord Hanuman is described as a human belonging to a tribe called ‘Vanar’. In Ramcharitmanas he is described as a monkey and ‘Vanar’ is used to refer to his specie of Monkeys.
3. There is no mention of Sita’s Swayamvara in Ramayan. There is no contest and Lord Parshuram never comes.
4. In Ramayan Ravan kidnaps Sita. After Ram rescues her, he asks her to prove her purity(although, he himself never doubted her) to the world by taking the test of fire(Agni Pariksha). According to Ramcharitmanas Ravan kidnaps a magically created duplicate of Sita as Ram foresees this and sends the real Sita to Agni Dev(the God of fire). The test of fire episode is just a way to take back the original and replace the duplicate.
5. Ravan enters the battlefield twice in Ramayan. First, on the first day when he is humiliated but left alive by lord Ram and then in the end. According to Ramcharitmanas he only comes in the end.
6. The story of Ramayan ends with Lord Ram ending his mortal incarnation by willfully drowning in water after being saddened by the death of Lakshman and Sita. Ramcharitmanas on the other hand never mentions the banishment if Sita or the death of Lakshman . It ends with the birth of twins Luv and Kush to Ram and Sita.
7. Ramayan in general portrays Ram as a hero, a human being with excellent virtues. Some of his deeds depicted can be debated as being right or wrong. Ramcharitmanas portrays him as the all knowing incarnation of God and has celestial and mystical touches to each of his deeds. His actions are shown to be 
8. God’s righteous ways to establish Dharma.

https://hindulegends.com/10-differences-between-ramayana-and-ramcharitmanas/

Clone

One of the Very Important Difference: Sita's Abduction.

Ramcharitra Manas:

1. Rama was aware of Sita’s Abduction. Hence, he had given Sita to Agni , and created the Clone of her. After Agni-Pariksha, the Clone goes in fire and real Sita returns.
2. Ravan hold of Sita’s hand, took her to Lanka in his Chariot.

Valmiki’s Ramayan:

1. Sita’s Abduction and suffering was real.
2. When ravaan tried to took hold of her, she tried to run & struggled alot to save herself. Tried to took hold of everything in-between to restrain herself. She took hold of nearby tree, Ravaan pulled her hairs, and dragged her to his Chariot.