Not all records are fully filed in so it's a bit pot luck.
The 1888 birth should have the full date. If you decide to order from GRO then ask for a .pdf rather than have a paper certificate posted.
https://www.gro.gov.uk/gro/content/certificates/faq.asp
1. Details contained on a full birth certificate include:
• Name, date and place of birth.
• Father's name (if given at time of registration), place of birth and occupation.
• Mother's name, place of birth, maiden surname and, after 1984, occupation.
Please note that registrations made before 1969 do not include details of the parents’ place
of birth and mother’s occupation.