to modify comparative adjectives.

To describe a small difference,

you can use the words 'a bit',

'a little' or 'slightly', for example:

'Tom is a bit taller than me.'

'Tom is a little taller than me'.

And 'Tom is slightly taller than me.'

To compare big differences, you can use

'a lot', 'significantly', 'far'  and 'much', for example:

'Physics is much more difficult than history.'

'Physics is a lot more difficult than history.'

'Physics is far more difficult than history.'

Or: 'Physics is significantly more  difficult than history.'

The final thing to mention is which words

can't be used with comparative adjectives.

'Very' and 'really' can never be used in

a comparative sentence.

Compare comparative adjectives with

'a bit', 'a little',  'slightly' for small differences,

or 'a lot', 'significantly', 'far' and 'much'

for big differences.