Ancla vs. áncora
'Ancla' and 'áncora' are two words in Spanish that refer to the same object usually associated with ships, the anchor. However, they are used differently based on geographical location and one is also considered obsolete.
Ancla
'Ancla' is the commonly used term for 'anchor' in modern Spanish-speaking countries. It refers to a heavy object attached to a rope or chain used to moor a vessel to the sea bottom, or a similar device used to hold an airship in place.
El barco lanzó el ancla para evitar ser arrastrado por la marea.
(The ship dropped anchor to prevent being carried away by the tide.)
Necesitamos un ancla más fuerte para resistir esta tormenta.
(We need a stronger anchor to withstand this storm.)
Áncora
'Áncora' also means 'anchor'. However, it is an obsolete term in Spanish and is rarely used in modern speech or writing. An exception might be found in literature, especially older or poetic works.
Su amor fue mi áncora en la tempestad de mi vida.
(His love was my anchor in the storm of my life.)
El marinero miraba con nostalgia hacia su vieja áncora, emblema de años en el mar.
(The sailor looked nostalgically at his old anchor, emblem of years at sea.)
Summary
Both 'ancla' and 'áncora' denote 'anchor' in Spanish language. While 'ancla' is widely used in modern day conversation among Spanish speakers, 'áncora' is very rare and considered obsolete with occasional appearances in poetry or classic literature.