The mechanical parts between the 1987-1991 Camry are virtually the same. The V6 Camry came out in mid-1988. 4-cylinder (3SFE) is the same for all years of the 2nd generation Camry.
As far as cosmetic, the 1987-1988 Camry fenders can be interchanged with one another, but not with an 89 Camry. This is because the front bumper on 1989 (and up) Camrys is one piece that goes around from the wheel wells on either side of the front of the car. On 1987-1988 Camrys the bumper only goes across the front an less around the sides (than 89), with plastic mouldings in front of the wheel wells to make the bumper look like one piece, but it's not. 1989 Camrys are compatible with 1990-1991 model Camrys, but the trunk on the 1991 Camrys is slightly altered (lights "flipped" upside down from previous years), along with the grille (1st year Toyota symbol we know today was used) and clear front turn signals as opposed to amber on older Camrys (these can be used on all 87-91 Camrys).
Some other notes: LE models have body colored trim and bumpers, DX and lesser models come with black trim and bumpers for all years except 1991 (base model bumpers were always black in this generation). All models have chrome door handles, except in 1991 when LE and DX got body colored door handles, while base model remained chrome.
Hope this helps! I also own a 1988 Camry (4cyl base model) myself.