A。 では、～B。

When to use

The topic-restriction particle ("as for X, among X"), NOT the それでは connective it looks like.

Explanation

The A では、～B grammar point is used to indicate a contrast or comparison between A and B. It is used to express that 'As for A, ~ B' or 'Regarding A, ~ B'. This grammar structure is often used for contrasting or comparing different subjects/topics.

• 果物くだものでは、リンゴが一番いちばん好すきです。

  As for fruits, apples are my favorite.

  Kudamono dewa, ringo ga ichiban suki desu.

• スポーツでは、サッカーが一番いちばん人気にんきです。

  As for sports, soccer is the most popular.

  Supōtsu dewa, sakkā ga ichiban ninki desu.

• 今日きょうの天気てんきでは、雨あめが降おりそうです。

  As for today's weather, it looks like it will rain.

  Kyou no tenki dewa, ame ga furisou desu.

• 料理りょうりでは、和食わしょくが一番いちばん得意とくいです。

  As for cooking, I am best at Japanese cuisine.

  Ryouri dewa, washoku ga ichiban tokui desu.

Comparison (More Than / Which / The Most)

• A は B より～A wa B yori～N5Express a comparison between A and B; 'A is more/less than…
• A より B のほうが～A yori B no hou ga ～N5Used to compare two items; 'B is more ～ than A'.
• A は B ほど～ありませんA wa B hodo ～ arimasenN4Express that A is not as much as B; 'not as... as'…
• A が いちばん～A ga ichiban～N5Express the superlative degree; 'the most', 'the best'…
• Aと Bと どちら～A to B to dochira~N5Used to ask which of two alternatives is preferred or to…
• AとBと どっち〜A to B to docchi〜N5Asking which one; 'which', 'A or B'.
• どちら～dochira～N5Used to ask about two choices or options.
• どの Noundono NounN5Expresses 'which'; used to ask about specific items within…
• もっと〜motto〜N5Expresses 'more' or 'even more' when describing a…
• ～というより〜to iu yoriN3Express a comparison with preference; 'rather than', 'more…
• ～に比べて〜ni kurabeteN3Comparing to; in comparison with; as opposed to.
• Noun とは比べものにならない~to wa kurabemono ni naranaiN1Indicates something is not comparable; 'beyond comparison'.
• Verbる くらいなら〜ru kurai naraN1Expresses preference to avoid something: 'rather than...'…

Compare when to use each