This is an overview of comparative forms in the Japanese language. When comparing two objects or factors the Japanese often use the particle より (yori), meaning "from", to describe that viewed from object "A", object "B" is heavier, smaller, more interesting, etc. The structure is then as follows:

"A"より"B"が面白い。
"A" yori "B" ga omoshiroi.
"B" is more interesting than "A".

If you do not wish to mention "A" you can use a structure with ほう (hō / 方), meaning "side", to describe that the side "which is" "B" is heavier, smaller, etc.

"B"のほうが高い。
"B" no hō ga takai.
"B" is more expensive.

These two constructions can be combined into one sentence:

"A"より"B"のほうがかわいい。
"A" yori "B" no hō ga kawaii.
"B" is cuter than "A".

Another construction uses もっと (motto), this construction can be used by itself and in combination with the より (yori) construction:

"A"より"B"がもっと安い。
"A" yori "B" ga motto yasui.
"B" is cheaper than "A".

In fact, all three constructions can be combined into one sentence:

"A"より"B"の方がもっときれいだ。
"A" yori "B" no hou ga motto kirei da.
"B" is more beautiful than "A".

Particular attention needs to be paid to the use and placement of the particles の (no) and が (ga). ほう (hou) should always be preceded by the particle の (no), and もっと (motto) should always precede the adjective.

Superlatives

Superlatives are constructed by placing 一番 (ichiban), meaning "number one", or 最も (mottomo), meaning "most", directly before the adjective.

"A"が一番大切だ。
"A" ga ichiban taisetsu da.
"A" is the most important.

"A"が最もいい。
"A" ga mottomo ii.
"A" is the best.

One can often encounter kanji combinations with 最 and the kanji for a verbal adjective. Both kanji then receive the on'yomi (or Chinese reading).

"A"が最高だ。
"A" ga saikou da.
"A" is the highest. / "A" is the greatest.

"A"が最低です。
"A" ga saitei desu.
"A" is the lowest. / "A" is the worst.

Identical

The Japanese word for "same" is 同じ (onaji), which when using in comparisons is always preceded by the particle と (to).

昔持った椅子と同じだ。
Mukashi motta isu to onaji da.
It's the same chair as I used to have.

When describing that "it's the same as mine", the Japanese tend to say と一緒 (to issho), meaning "together with", rather than と同じ, meaning "the same as".

あの財布は彼と一緒だ。
Ano saifu wa kare to issho da.
That's the same wallet as he has.

あの財布は彼のと同じだ。
Ano saifu wa kare no to onaji da.
That's the same wallet as he has.

Note the use of の (no) to make the personal pronoun 彼 (kare) a possessive pronoun.

Similarity

To indicate that two objects or factors are about the same, 位 (gurai) is added after 同じ (onaji).

昔持った椅子と同じぐらいだ。
Mukashi motta isu to onaji gurai da.
It's about the same chair as I used to have.