前者は・後者は

ぜんしゃは・こうしゃは

The former ~ the latter, The first ~ the second

地下鉄ちかてつと新幹線しんかんせん、前者ぜんしゃは地下ちかをゆっくりと走はしり、後者こうしゃは速はやいスピードで地上ちじょうを走はしる。

Subways and bullet trains. The former runs slowly underground, and the latter runs above ground at a high speed.

Explanation

After two things (A and B) have been named, 「前者は〜、後者は〜」 explains each in turn: 「前者」 is the first one mentioned, 「後者」 the second. Common in explanatory and academic writing: 「AとBがある。前者は〜、後者は〜」 (There are A and B. The former is ..., the latter is ...).

Mixed up with

Reading questions often ask what an underlined 「前者」 refers to: find the first of the two items listed in the previous sentence, and don't be misled by earlier sentences.

Only for written explanations, essays and reports. In speech people say 「最初のは〜、あとのほうは〜」.

Examples

そうめんと冷麦ひやむぎ、前者ぜんしゃは細ほそく、後者こうしゃは少すこし太ふとい。
Somen and hiyamugi: the former is thin, the latter is a little thicker.
こっちの車くるまとこっちの車くるまどっちを買かおう。前者ぜんしゃは安やすくて古ふるくて、後者こうしゃは高たかくて新あたらしい。
This car or that car, which should I buy? The former is cheap and old, and the latter is expensive and new.
ダンゴムシとワラジムシ、前者ぜんしゃは触さわると丸まるまり、後者こうしゃは触さわっても丸まるまらないという違ちがいがあります。
Pill bugs and sow bugs differ: the former rolls into a ball when touched, the latter doesn't.
どの大学だいがくに行いくか迷まよっています。前者ぜんしゃは家いえに近ちかいが学費がくひが高たかい、後者こうしゃは家いえから遠とおいが学費がくひが半分はんぶんぐらい安やすい。
I am undecided on which college to go to. The former is close to my house, but the tuition is expensive. The latter is far from my house but the tuition is almost half the price.
宿泊しゅくはく場所ばしょの候補こうほが二ふたつあります。前者ぜんしゃは温泉おんせんがあり、後者こうしゃはご飯はんがおいしいです。
There are two choices for places to stay. The first has hot springs, the second has delicious food.
交通こうつうの札ふだには切符きっぷと整理券せいりけんの二ふたつがあります。前者ぜんしゃは電車でんしゃに乗のるために必要ひつようなもので、後者こうしゃはバスに乗のるときに取とるものです。
There are two types of transportation tickets: 'kippu' and 'seiriken'. The former is a thing needed for getting on a train, and the latter is taken when boarding on a bus.
どちらのパソコンがいいですか？前者ぜんしゃは安やすいが性能せいのうは一般いっぱん向むけ、後者こうしゃは高たかいが高性能こうせいのう。
Which laptop is better? The former is cheap, but the specifications are average. The latter is expensive, but has better performance.
どちらの家いえにするか迷まよっています。前者ぜんしゃは駅えきから近ちかいが家賃やちんが高たかい、後者こうしゃは駅えきから遠とおいが家賃やちんも安やすく部屋へやも広ひろい。
I can't decide which house to rent. The former is close to the nearest station, but expensive. The latter is far from the station, but cheap and spacious.
どちらのコートがいいだろう…。前者ぜんしゃは相当そうとう温あたたかいが春秋しゅんじゅうには着きられない。後者こうしゃはそこまで温あたたかくないが春はるも秋あきも冬ふゆも着きられる。
Which coat should I get... The former is very warm, but I can't wear it in spring and autumn. The latter isn't that warm, but I can wear it in spring, autumn and winter.
Ａ社しゃとＢ社しゃ、どちらに就職しゅうしょくするか迷まよっています。前者ぜんしゃは給料きゅうりょうがよく、後者こうしゃは環境かんきょうがいいのです。
I am having trouble deciding between company A and company B. The former's pay is good and the latter has a good working environment.
洋服ようふくと着物きものどちらがいいかな？前者ぜんしゃはすぐに準備じゅんびできる。後者こうしゃは準備じゅんびが大変たいへんだが、きっと喜よろこばれる。
Which should I wear, western clothes or kimono? I can just throw on the former. The latter is hard (to put on), however it will make them happy for sure.
ラーメンと寿司すしどちらにしよう？前者ぜんしゃは安やすくて気軽きがるに食たべられるが少すこし脂あぶらっこい。後者こうしゃは美味おいしいしいろいろなネタを楽たのしめるが少すこし高たかくつく。
Which should I get, ramen or sushi? The former is cheap but quite greasy. The latter is tasty, and you can enjoy many kinds, but gets a bit expensive.
参考さんこう図書としょはこちらとこちらの二に冊さつです。前者ぜんしゃは手てに入いれやすいのですが、後者こうしゃは絶版ぜっぱんで手てに入いれるのが難むずかしいです。
As for reference books, there are these two. The former one is easy to obtain. However, the latter is out of print and, therefore, hard to find.
私わたしの好すきな詩人しじんはＡさんとＢさんです。前者ぜんしゃはリズム感かんがよく、後者こうしゃは共感きょうかんできる内容ないようの詩しが得意とくいです。
My favorite poets are A-san and B-san. The former has a good sense of rhythm and the latter is good at poetry you can sympathize with.