When Romeo first appears in the play, he has a negative attitude to love because he is refused by Rosaline, shown in the quote, "She'll not be hit by Cupid's arrow." Being shot by Cupid is a metaphor for falling in love, and as Rosaline can not be hit, Romeo is saying that she does not love him back. This explanation of Romeo's love for Rosaline is undermined further down the speech when Romeo says, "Nor ope her lap to saint-seducing gold." This line contrasts greatly with the rest of what Romeo says as it literally means she will not have sex with him even if he pays her. Additionally, the fact that the gold is described as, "saint-seducing" explains that even Saints would give in but Rosaline does not, showing her stubbornness in retaining her virginity. This request shows that Romeo has a surprisingly forward attitude to love but also strongly questions whether Romeo has a lust, not a love for Rosaline; and if he knows what love is at all.
Strengthening the idea that Romeo has a lust for Rosaline, Romeo's feelings towards Rosaline are often compared with nature, for example, "adding to clouds more clouds with his deep sighs." Traditionally, this poetical technique, called, 'Pathetic Fallacy' is used to describe the vastness of an emotion by comparing it to a force as strong as nature. But in this case, I think it has been used because nature is often used to describe beauty, but rarely love.
In contrast, Romeo's love for Juliet, at the moment he meets her and throughout the play, is compared to Religion, for example, Romeo likens juliet to a, "fruit tree." This tree represents the tree of life in Adam and Eve, a tale from the bible. When Romeo calls juliet a fruit tree, he is saying she is causing him to act sinfully, as in Adam and Eve the fruit from the tree of life causes the couple to be sinful and defy god's rule. In addtition, Adam is exiled from the garden of Eden for eating the fruit from the tree of life; this could be foreshadowing Romeo's exile, and the eating of the fruit could be a euphamism for Romeo taking Juliet's virginity. These continuous links to Religion show that Romeo thinks of Juliet as a Goddess, even explaining that he worships her. The fact that this level of admiration and love has developed within seconds of meeting each other, as well as Romeo's instant dismissal of Rosaline shows they are instantly in love, and despite furthering the idea that Romeo has a naive attitude to love in that he has fallen for Juliet in seconds, it proves that Romeo understands love and feels it for the first time. This instant connection would appeal to the audience's emotional side as they would realise the depth of Romeo and Juliet's love for each other.