原来 / 本来

yuánlái / běnlái

Similarities

Both 原来 and 本来 can be adjectives meaning “original” or “former”, and both as adverbs can say the past differed from now.

这(Zhè)是(shì)它(tā)原(yuán)来(lái)的(de)颜(yán)色(sè)，不(bù)过(guò)现(xiàn)在(zài)已(yǐ)经(jīng)穿(chuān)了(le)好(hǎo)几(jǐ)年(nián)，颜(yán)色(sè)都(dōu)变(biàn)了(le)。

This was its original colour, but after several years of wear the colour has changed.

这(Zhè)是(shì)它(tā)本(běn)来(lái)的(de)颜(yán)色(sè)，不(bù)过(guò)现(xiàn)在(zài)已(yǐ)经(jīng)穿(chuān)了(le)好(hǎo)几(jǐ)年(nián)，颜(yán)色(sè)都(dōu)变(biàn)了(le)。

This was its original colour, but after several years of wear the colour has changed.

我(Wǒ)家(jiā)原(yuán)来(lái)住(zhù)这儿(zhèr)附(fù)近(jìn)，不(bù)过(guò)这(zhè)里(lǐ)以(yǐ)前(qián)不(bù)像(xiàng)现(xiàn)在(zài)有(yǒu)这(zhè)么(me)多(duō)楼(lóu)房(fáng)。

My family used to live near here, but back then there weren't nearly as many buildings.

In these sentences 原来 and 本来 are interchangeable.

我(Wǒ)还(hái)以(yǐ)为(wéi)是(shì)谁(shéi)帮(bāng)我(wǒ)打(dǎ)扫(sǎo)房(fáng)间(jiān)呢(ne)，原(yuán)来(lái)是(shì)你(nǐ)啊(a)！

I was wondering who had cleaned my room. It turns out it was you!

这(Zhè)本(běn)书(shū)本(běn)来(lái)应(yīng)该(gāi)昨(zuó)天(tiān)还(huán)给(gěi)你(nǐ)，真(zhēn)不(bù)好(hǎo)意(yì)思(si)。

I should have returned this book to you yesterday. I'm really sorry.

原来	本来
it turns out…	originally… / should have…
a newly discovered fact	the original plan or expectation
expresses realisation	expresses what was supposed to happen

原来 → a newly discovered fact 本来 → the original situation, plan or expectation