ones/those

They are both "grammatically correct". The first is less formal.

Thanks, Contrex.

I think the first sentence is very awkward-sounding.

It's a strange fact though, if you say anything often enough, it starts to sound odd.

Agreed, McTag. I think you would use "ones" about definite things rather than undefined things, e.g.

The buses in London are bigger than the ones in Cambridge.
The dinner I had in Scotland was better than the one I had in Wales.

But it would better to use "those" in the plural case, and "that which" in the singular.

The churches in Oxford are prettier than those in Cambridge.
The dinner I had in Bristol cost less than that which I had in York.

In fact, the two sentences of Yoong Liat have bad problems. "Some" implies undefinedness, whereas "those" means "all". Also "a country" is odd. Which country? If you don't say, it makes the sentences rather pointless. They should be re-written thus:-

(1) Some proverbs in one country may be quite similar to some in another.

(2) Some proverbs in one country may be quite similar to some of those in another.

Hi Contrex

I agree that the sentences I posted are not well-phrased, and your sentences are certainly much clearer.

Regards