identification card身分証明書 means “identification card” or “ID”; を marks it as the object of the verb. This phrase is usually followed by a verb such as 見せる (to show), 提示する (to present), or 出す (to take out).
JA: 受付で身分証明書を見せてください。
EN: Please show your identification card at the reception desk.
ID身分証明書 means an identification document or ID, and を marks it as the object of the verb. The phrase commonly appears before verbs such as 見せる (to show), 持ってくる (to bring), or 忘れる (to forget).