There are righteous people who can be called “those who love God,” because they are willing to give up their lives to sanctify His name. There are other righteous people who, even though they observe the mitzvot, cannot be included in this category.

“Those who love Him” [based on Exodus 20:6] refers to those who sacrifice their lives for Him. For those who accept the Lord’s name and His exclusive divinity, denying any foreign god and refusing to serve them even if that endangers their lives, are referred to as “those who love Him.” For this is the type of love to which we committed ourselves with our lives, as the verse states: “You shall love the Lord your God with all your heart, and with all your soul, and with all your might” (Deuteronomy 6:5). This means that you should give up your soul and your life out of your love of Him, not exchanging Him for any other god, and not serving Him in partnership with any foreign god…The rest of the righteous [who do not sacrifice their lives] are called “those who observe His commandments” [also based on Exodus 20:6 and Deuteronomy 7:9]. (Ramban, Commentary on the Torah, Exodus 20:6)

Further reading: For more on self-sacrifice, see the accounts of the deaths of Rabbi Akiva and Rabbi Hanina, A Concise Guide to the Sages, p. 364.